Gearbox assembly with sealed housing

ABSTRACT

Electric motors are disclosed. The motors are preferably for use in an automated vehicle, although any one or more of a variety of motor uses are suitable. The motors include lift, turntable, and locomotion motors.

CROSS-REFERENCE TO RELATED APPLICATIONS

1. Priority Application

The present application claims priority from U.S. ProvisionalApplication No. 62/088,463, filed Dec. 5, 2014, the entire disclosure ofwhich is hereby incorporated by reference herein.

2. Contemporaneously Filed Applications

The present application is filed contemporaneously with U.S. patentapplication Ser. No. 14/960,138, entitled SHAFT SLEEVE PROVIDINGSEAL-ENGAGING SURFACE, filed Dec. 4, 2015; U.S. patent application Ser.No. 14/960,147, entitled SHIMLESS GEAR TRANSMISSION, filed Dec. 4, 2015;U.S. patent application Ser. No. 14/960,149, entitled STATOR WINDINGTHERMAL PROTECTOR SUPPORT, filed Dec. 4, 2015; U.S. patent applicationSer. No. 14/960,153, entitled DYNAMIC SEALING ENCODER ASSEMBLY, filedDec. 4, 2015; U.S. patent application Ser. No. 14/960,156, entitledMOTOR CASE WITH INTEGRATED WIRE SEALING STRUCTURE, filed Dec. 4, 2015;and International Application No. PCT/US15/64092, entitled ELECTRICMOTOR, filed Dec. 4, 2015. The entire disclosure of each of theaforementioned contemporaneously filed applications is herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an electric motor. The motoris preferably for use in an automated vehicle or, more particularly, ina robot for use in a warehousing system. However, any one or more of avariety of motor uses are suitable.

2. Discussion of the Prior Art

Those of ordinary skill in the art will appreciate that electric motorsare often used in a variety of applications, including but not limitedto vehicles, automated devices, home appliances such as dishwashers andwashing machines, exercise equipment, pumps, and more.

SUMMARY

According to one aspect of the present invention, a gearbox assembly isprovided. The gearbox assembly comprises a housing defining a gearchamber; a plurality of gears received in the gear chamber, with thehousing being configured to contain gear lubricant within the gearchamber; and a seal. The housing includes housing portions abutting eachother along an interface exposed to the gear chamber. The seal ispositioned along the interface to restrict leakage of lubricant throughthe interface. The housing defines an overflow chamber adjacent theinterface, such that the interface and the seal are disposed between thegear chamber and the overflow chamber.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Preferred embodiments of the invention are described in detail belowwith regard to the attached drawing figures, wherein:

FIG. 1 illustrates a robot, shelving, and goods, wherein the robot isoperable to transport the shelving and goods;

FIG. 2 illustrates the robot of FIG. 1, including the turntable, lift,and locomotion motors provided in the robot in accordance with apreferred embodiment of the present invention;

FIG. 3 is a top perspective view of the turntable motor of FIG. 2;

FIG. 4 is a bottom perspective view of the turntable motor of FIGS. 2and 3;

FIG. 5 is a bottom perspective view of the turntable motor of FIGS. 2-4,with the connection box cover removed;

FIG. 6 is a top perspective view of the turntable motor of FIGS. 2-5,particularly illustrating the gear assembly;

FIG. 7 is top perspective view of a portion of the turntable motor ofFIGS. 2-6;

FIG. 8 is a top perspective view of a portion of the turntable motor ofFIGS. 2-7, particularly illustrating the gear assembly, the oil sealingsystem, and the sealing sleeve;

FIG. 9 is a cross-sectional side view of a portion of the turntablemotor of FIGS. 2-8, particularly illustrating the gear assembly, the oilsealing system, and the sealing sleeve;

FIG. 10 is an enlarged cross-sectional side view of a portion of theturntable motor of FIGS. 2-9, particularly illustrating the gearassembly, the oil sealing system, and the sealing sleeve;

FIG. 10a is an enlarged top perspective view of a portion of a turntablemotor in accordance with a second preferred embodiment of the presentinvention, particularly illustrating an alternative sealing sleeveembodiment;

FIG. 11 is a perspective view of the stator of the turntable motor ofFIGS. 2-10, particularly illustrating the thermal protector assemblies;

FIG. 12 is a perspective view of the stator of the turntable motor ofFIGS. 2-11, particularly illustrating the thermal protector assemblies;

FIG. 13 is perspective view of a pair of end caps of the stator of theturntable motor of FIGS. 2-12;

FIG. 14 is an exploded perspective view of the pair of end caps of FIG.13;

FIG. 15 is a top perspective view of one of the thermal protectorassemblies of the stator of the turntable motor of FIGS. 2-12;

FIG. 16 is a bottom perspective view of the thermal protector assemblyof FIG. 15;

FIG. 17 is an enlarged perspective view of the stator and a thermalprotector assembly of the turntable motor of FIGS. 2-12;

FIG. 18 is a cross-sectional perspective view of the stator and thermalprotector assembly of FIG. 17;

FIG. 19 is a rear perspective view of the lift motor of FIG. 2;

FIG. 20 is a front perspective view of the lift motor of FIGS. 2 and 19;

FIG. 21 is a rear perspective view of the lift motor of FIGS. 2, 19, and20;

FIG. 22 is a partially sectioned rear perspective view of the lift motorof FIGS. 2 and 19-21;

FIG. 23 is a front view of the lift motor of FIGS. 2 and 19-22,particularly illustrating the lift arm positionability and the lift armstops;

FIG. 24 is a front perspective view of the lift motor of FIGS. 2 and19-23, particularly illustrating the lift arm positionability and thelift arm stops;

FIG. 25 is front view of the lift motor of FIGS. 2 and 19-24,particularly illustrating the lift arm positionability and the lift armstops;

FIG. 26 is a front perspective view of the lift motor of FIGS. 2 and19-25, particularly illustrating the lift arm positionability and thelift arm stops;

FIG. 27 is a front view of the lift motor of FIGS. 2 and 19-26,particularly illustrating the lift arm positionability and the lift armstops;

FIG. 28 is a front perspective view of the lift motor of FIGS. 2 and19-27, particularly illustrating the lift arm positionability and thelift arm stops;

FIG. 29 is a front perspective view of a portion of the lift motor ofFIGS. 2 and 19-28;

FIG. 30 is an exploded front perspective view of the lift motor of FIGS.2 and 19-29;

FIG. 31 is an exploded rear perspective view of the lift motor of FIGS.2 and 19-30;

FIG. 32a is a cross-sectional side view of the lift motor of FIGS. 2 and19-31, particularly illustrating the gear system;

FIG. 32b is a schematic front view of the first stage of the gearsystem;

FIG. 32c is a schematic front view of the second stage of the gearsystem;

FIG. 33 is an outer perspective view of one of the locomotion motors ofFIG. 2;

FIG. 34 is an inner perspective view of the locomotion motor of FIGS. 2and 33;

FIG. 35 is a partially cross-sectioned outer perspective view of aportion of the locomotion motor of FIGS. 2, 33, and 34;

FIG. 36 is a partially cross-sectioned inner perspective view of aportion of the locomotion motor of FIGS. 2 and 33-35;

FIG. 37 is an exploded inner perspective view of the locomotion motor ofFIGS. 2 and 33-36, particularly illustrating the integrated wireconnection and sealing mechanism;

FIG. 38 is an exploded outer perspective view of the locomotion motor ofFIGS. 2 and 33-37, particularly illustrating the integrated wireconnection and sealing mechanism;

FIG. 39 is an enlarged view of a portion of the output encoder assemblyof the locomotion motor of FIGS. 2 and 33-38;

FIG. 40 is an enlarged, exploded outer perspective view of the outputencoder assembly of the locomotion motor of FIGS. 2 and 33-39;

FIG. 41 is an enlarged, exploded inner perspective view of the outputencoder assembly of the locomotion motor of FIGS. 2 and 33-40;

FIG. 42a is a cross-sectional side view of the locomotion motor of FIGS.2 and 33-41, particularly illustrating the gear system;

FIG. 42b is a schematic front view of the gear system;

FIG. 43 is an inner perspective view of the locomotion motor of FIGS. 2and 33-42 b, particularly illustrating the integrated wire connectionand sealing mechanism;

FIG. 44 is a perspective view of the stator and shell of the locomotionmotor of FIGS. 2 and 33-43, particularly illustrating theinterconnection of the stator and the shell;

FIG. 45 is an enlarged, cross-sectional end view of the stator and shellof FIG. 44, particularly illustrating the interconnection of the statorand the shell; and

FIG. 46 is an enlarged, cross-sectional side view of the stator andshell of FIGS. 44 and 45, particularly illustrating the interconnectionof the stator and the shell.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred embodiment of the present invention, a robot 10 isprovided. The robot 10 preferably includes a main body 12 supported on achassis (not shown), a support platform 14, and a pair of wheels 16enabling the robot 10 to have a zero-turn radius.

The robot 10 is preferably configured to transport goods in a warehouseenvironment. For instance, in a preferred embodiment, the robot 10 isconfigured to transport shelving 18 and various goods 20 supportedthereon through a warehouse environment. More particularly, the robot 10is preferably operable at least to (1) lift the shelving 18 andassociated goods 20 on the platform 14; (2) rotate at least a portion ofthe platform 14 so as to appropriately orient the shelving 18 and goods20 supported by the platform 14; (3) transport the shelving 18 and goods20 on the platform 14 from one location to another in the warehouse,making use of the wheels 16; (4) deposit the shelving 18 and goods 20 attheir new location through lowering of the platform 14; and (5)completely disengage from the shelving 18 and goods 20 via lowering ofthe platform 14 so as to no longer be in contact with the shelving 18and/or goods 20.

The robot 10 is preferably provided with numerous features to enablesuch operation, including but not limited to one or more printed circuitboards, sensors, cameras, and communication devices. A control system(not shown) is also preferably provided to control each robot 10 and tosynchronize operation of multiple robots 10 in a warehouse.

Preferably, some embodiments of the robot 10 are able to transport loadsas large as three thousand (3,000) pounds.

The robot 10 is preferably battery-powered and rechargeable.

In a preferred embodiment, the robot 10 includes four (4) motors: aturntable motor 100 operable to rotate and stabilize at least a portionof the platform 14; a lift motor 500 operable to raise the platform 14,preferably but not necessarily with the assistance of a scissor liftmechanism or other lifting aid; and a pair of locomotion motors 700,each of which is associated with a respective one of the wheels 16, andwhich cooperatively enable the robot 10 to travel through the warehouse.Each of these motors 100, 500, 700 will be described in detail below.

Preferably, the turntable motor 100 is mounted to the platform 14. Thelift motor 500 and the locomotion motors 700 are preferably mounteddirectly to the chassis.

Although the turntable motor 100, the lift motor 500, and the locomotionmotors 700 are preferably part of the robot 10 and function generally asdescribed above, it is noted that it is within the scope of the presentinvention for the motors to instead be provided in an alternativeapplication and/or to be provided separately from one another. Forinstance, the locomotion motors might instead be provided for use in anelectric vehicle for human transport, the turntable motor might be usedto operate a rotating display, or the lift motor might be used to raiseand lower a load that is in no manner associated with a warehouseoperation. Furthermore, certain features of each of the motors may beused in entirely different applications than shown. For example, certainaspects of the locomotion motor might be capable of use in motors thatare not used to drive or propel a wheeled vehicle.

Turntable Motor

A preferred embodiment of the turntable motor 100 is shown in detail inFIGS. 3-18. The turntable motor 100 is preferably a three-phase,direct-current (DC) brushless permanent magnet (BPM) motor, althoughcertain features described below are suitable for use with alternativelyphased or configured motors. For instance, certain features are suitablefor use on a single phase motor, an AC motor, and/or an induction motor.

Among other things, the turntable motor 100 preferably includes a rotor110 rotatable about an axis, a stator 112, and a gearbox assembly 114.The turntable motor is preferably oriented such that the axis is avertical axis. The rotor 110 and stator 112 are preferably positioned atan axially downward end of the turntable motor 100, while the gearboxassembly 114 is positioned at an axially upward end of the turntablemotor 100. It is permissible according to some aspects of the presentinvention, however, for the turntable motor to be alternativelyoriented. That is, unless otherwise specified or made clear, thedirectional references made herein with regard to the turntable motor100 (e.g., top, bottom, upper, lower, etc.) are used solely for the sakeof convenience and should be understood only in relation to each other.For instance, a component might in practice be oriented such that facesreferred to as “top” and “bottom” are sideways, angled, inverted, etc.relative to the chosen frame of reference.

As will be discussed in greater detail below, the gearbox assembly 114preferably engages the platform 14 such that the turntable motor 100causes rotation of the platform 14.

Stator Overview

As best shown in FIGS. 11 and 12, the stator 112 preferably includes agenerally toroidal stator core 116 and wiring 117 wound about the statorcore 116 to form a plurality of coils 118. The stator core 116 ispreferably a laminated stator core, although it is permissible for thestator core to be non-laminated. The stator core 116 preferablycomprises a ferromagnetic material such as steel, although use of anyone or more electrically conductive materials is permissible withoutdeparting from the scope of the present invention. In a preferredembodiment, for instance, the stator core 116 is formed from 0.0185 or0.195 inch thick c5 core plate. Preferably, no stress annealing occursafter punching of the laminations. Other gauges, processing techniques,and grades fall within the scope of the present invention, however.

The laminations of the stator core 116 are preferably interlocked torestrict relative axial shifting, although other configurations (e.g.,non-interlocked laminations) are permissible.

The stator core 116 preferably defines an axis. Most preferably, theaxis is co-axial with the axis of the rotor 110, although offset orskewed axes are permissible according to some aspects of the presentinvention.

Preferably, the stator core 116 includes a plurality of arcuately spacedapart, generally radially extending teeth 120. More particularly, in apreferred embodiment, each of the teeth 120 includes a generallycircumferentially extending yoke 122, a generally radial arm 124extending from the yoke 122 and having an end 126, and a crown 128extending generally circumferentially from the end 126.

The turntable motor 100 is preferably an inner rotor motor, with thestator 112 at least substantially circumscribing the rotor 110 (in amanner similar to that shown in FIG. 29 for the lift motor 500). Moreparticularly, each yoke 122 preferably engages a pair of adjacent yokes122, such that the yokes 122 cooperatively present an outercircumferential stator core face 130. The crowns 128 cooperativelypresent a discontinuous inner circumferential stator core face 132 thatfaces the rotor 110. As will be discussed in greater detail below, acircumferentially extending radial gap (not shown) is preferably formedbetween the inner circumferential stator core face 132 and the rotor110.

Each tooth 120 preferably presents an upper tooth face 134, a lowertooth face 136, and two side tooth faces 138. The teeth 120 preferablycooperatively present an upper stator core face 140 and a lower statorcore face 142.

In a preferred embodiment, the stator core 116 has an axial length ofabout one and five tenths (1.5) inches measured from the upper statorcore face 140 to the lower stator core face 142, an outside diameter ofabout five and four hundred ninety thousandths (5.490) inches, and aninside diameter of about three and two hundred thirty-four thousandths(3.234) inches.

It is permissible according to some aspects of the present invention forthe stator core to be alternatively configured, however. Among otherthings, for instance, the stator core could comprise a plurality ofinterconnected multi-tooth segments, comprise one or more helicallywound laminations, or comprise stacked annular laminations each formedfrom a single punched strip. Furthermore, the aforementioned preferredlength and gap dimensions may vary without departing from the scope ofthe present invention.

As will be discussed in greater detail below, the stator core 116 ispreferably electrically insulated by means of a plurality of discrete,electrically insulative end caps 144 secured relative to the core 116.However, it is noted that use of any one or more of a variety ofinsulation means, including but not limited to the use of electricallyinsulative overmolding, powder-coating, and/or liners, is permissibleaccording to some aspects of the present invention. It is alsopermissible according to some aspects of the present invention for thestator core to be devoid of electrical insulation.

The coils 118 are preferably wound about the arms 124 of the teeth 120.More particularly, a slot 146 is defined between each adjacent pair ofteeth 120. The coils 118 are preferably wound about the teeth 120 andthrough the slots 146 so as to circumscribe respective ones of the arms124.

The coils 118 preferably comprise electrically conductive wiring wiring117. The wiring 117 is preferably wound multiple times about each tooth120 to form a plurality of turns or loops. The wiring 117 is preferablyformed of copper or aluminum, although any one or more of a variety ofelectrical conductive materials or a combination thereof may be usedwithin the ambit of the present invention.

Furthermore, the wiring 148 may be coated or uncoated.

As is customary, the wiring 148 is wound around the teeth 120 in aparticular manner according to the configuration and desired performancecharacteristics of the turntable motor 100.

The turntable motor 100 preferably includes twelve (12) teeth 120defining twelve (12) slots 146.

Rotor Overview

As best shown in FIG. 8, the rotor 110 preferably includes a rotor core150, a plurality of arcuately arranged magnets 152, and a motor shaft154.

The rotor core 150 is preferably a laminated rotor core, although it ispermissible for the rotor core to be non-laminated. The rotor core 150preferably comprises a ferromagnetic material such as steel, althoughuse of any one or more electrically conductive materials is permissiblewithout departing from the scope of the present invention. In apreferred embodiment, for instance, the rotor core 150 is formed fromthirty-one thousandths (0.031) inch laminations of semi-processed S85steel. Preferably, the rotor core 150 is annealed as a partially fluffedcore. Other gauges, processing techniques, and grades fall within thescope of the present invention, however.

The laminations of the rotor core 150 are preferably interlocked,although other configurations (e.g., non-interlocked laminations) arepermissible.

Rotor Magnet Securement

The rotor core 150 is preferably generally octagonal in cross-section soas to define a plurality of magnet-mounting faces 156, although othershapes (e.g., round or hexagonal) are permissible according to someaspects of the present invention.

Each magnet-mounting face 156 preferably includes a recessed centralportion 156 a, a pair of side portions 156 b on opposite sides of thecentral portion 156 a, and a pair of grooves 156 c adjacent and outsidethe side portions 156 b.

Retaining walls 157 are preferably formed by the rotor core 150 adjacentthe magnet-mounting faces 156 and may restrict circumferential shiftingof the magnets 152 if necessary.

The magnets 152 are preferably mounted to corresponding ones of themagnet-mounting faces 156 through use of a glue or adhesive. In apreferred embodiment, for instance the magnets 152 are retained on themagnet-mounting faces 156 through use of a two step acrylic, one-part,dual-cure, thixotropic magnet bonding adhesive with a solvent-lessactivator (e.g., Loctite® 334™ Structural Adhesive in conjunction withLoctite® 7380™ Depend® Activator).

The adhesive is preferably applied to each magnet-mounting face 156 andto each magnet 152. The adhesive may applied in the form of a bead, in apattern (e.g., a grid or a plurality of evenly spaced apart dots), in arandom dispersion, or over the entire surface.

The rotor 110 is preferably additionally wrapped with a thin film (notshown) to provide redundant magnet 152 retention. Preferably, the filmis heat shrunk over the rotor 110. In a preferred embodiment, forinstance, the rotor 110 is wrapped in a seven thousandths (0.007) inchthick Mylar® spiral-wound tube which is then heat shrunk onto the motor.After heat shrinking, the thickness preferably increases to about tenthousandths (0.010) inches.

In a preferred embodiment, the film has a tensile strength of betweenabout twenty-six thousand (26,000) psi and about forty-five thousand(45,000) psi.

In addition to providing retention of the magnets 152 in whole, the thinfilm is also preferably operable to retain any chips that might breakaway from the magnets 152. (The likelihood of such chip formation isgreater if a non-preferred magnet material such as ferrite is used,rather than the previously described preferred, unlikely-to-chipneodymium iron boron magnet material.)

The magnet retention means may vary from the preferred combinationdescribed above without departing from some aspects of the presentinvention, however. For instance, it is permissible according to someaspects of the present invention for the thin film to be omitted and/orfor the magnets to be retained using alternative or additionalmechanical means or an alternative or additional adhesive. Preferably,however, the magnet retention means are sufficient to restrict magnetdislodgement at all speeds of the turntable motor 100.

In a preferred embodiment, for instance, the turntable motor 100 has ahigh speed of about three thousand, six hundred thirty (3,630) rpm and amaximum speed of about three thousand, six hundred forty (3,640) rpm.Such speeds, in combination with a preferred magnet 152 mass of aboutfifteen and three tenths (15.3) grams and the radial positioning of themagnets 152 relative to the axis of rotation lead to centrifugal magnetforces of about eighteen and seven tenths (18.7) lb. The magnets 152 mayalso be subject to radial forces of about thirty-one and eight tenths(31.8) lb due to the maximum motor torque force of about thirty-one andeight tenths (31.8) lb (i.e., about seven and ninety-five hundredths(7.95) lb/magnet, wherein the radial magnetic force is approximatelyfour (4) times the torque force).

The magnet retention means should also be sufficient to restrict magnetdislodgement at all possible magnet temperatures during operation. In apreferred embodiment, for instance, the magnet retention means functionacceptably when the magnets 152 are at temperatures between about zerodegrees Celsius (0° C.) and a predicted maximum temperature of abouteighty-five and three tenths degrees Celsius (85.3° C.).

The magnets 152 are preferably rare earth magnets. More particularly,the magnets 152 are preferably thirty-five (35) uh (one hundred eightydegrees Celsius (180° C.) grade neodymium iron boron magnets. Othermagnet types may be used without departing from some aspects of thepresent invention, however. For instance, according to some aspects ofthe present invention, the magnets might be of a lower grade and/orcomprise ferrite.

In a preferred embodiment, the magnets 152 include nickel-copper-nickelplating. Alternative plating or no plating is permissible, however.

The magnets 152 preferably have a “bread loaf” geometry, including aflat base 158 for mounting to the corresponding magnet-mounting face156, a pair of flat sidewalls 160, flat front and rear walls 162, and arounded top 164. The tops 164 preferably cooperatively present an outercircumferential rotor face 166.

The gap is preferably formed between the inner circumferential statorcore face 132 and the outer circumferential rotor face 166. The gappreferably has a minimum radial dimension of about one (1) mm.

In a preferred embodiment, eight (8) magnets 152 are provided and defineeight (8) poles. Each magnet 152 is preferably about eighty-onehundredths (0.81) inches in length and extends along an arc of aboutthirty-two degrees (32)°. Magnet numbers and dimensions may vary withinthe ambit of the present invention, however.

In keeping with the above-described preferred stator core 116, whichdefines twelve (12) slots, it is noted that the turntable motor 100 ispreferably a twelve (12) slot, eight (8) pole motor. It is permissibleaccording to some aspects of the present invention, however, for theturntable motor to have a different number of slots and polesmaintaining the preferred three (3) slot:two (2) pole ratio or for anentirely different slot to pole ratio to be defined.

In a preferred embodiment, the rotor core 150 presents upper and lowerrotor core faces 168 and 170, respectively. The rotor core 150preferably has an axial length of about one and five tenths (1.5) inchesmeasured between the upper and lower rotor core faces 168 and 170. Themagnets 152 are preferably sized so as to not extend past the upper andlower rotor core faces 168 and 170 (i.e., the magnets 152 preferablyhave an axial length less than or equal to one and five tenths (1.5)inches).

Stator Core Insulation

As noted previously, the stator core 116 is preferably insulated bymeans of a plurality of end caps 144 fitted over portions of the teeth120. Each end cap 144 preferably comprises an electrically insulativematerial. For instance, a plastic or synthetic resin material may beused.

In a preferred embodiment and as best shown in FIGS. 11 and 12, each endcap 144 provides both a physical and electrical barrier between thecoils 118 and the stator core 116, with a pair of end caps 144 fittedover opposite axial sides (corresponding to upper and lower stator corefaces 140 and 142) of a corresponding tooth 120 and engaging one anotherat an end cap juncture 172 so as to in part encompass the tooth 120.

More particularly, as shown in detail in FIGS. 13 and 14, each end cap144 includes a yoke portion 174, an arm portion 176, and a crown portion178 corresponding to the yoke 122, arm 124, and crown 128 of acorresponding tooth 120. Each yoke portion 174 extends along at least aportion of a corresponding one of the upper and lower axial tooth faces134 and 136. Preferably, the outer circumferential stator core face 130cooperatively defined by the yokes 122 is left exposed. The arm portions176 of a corresponding pair of end caps 144 preferably cooperativelyfully circumscribe the corresponding arms 124. Furthermore, the crownportions 178 of a corresponding pair of end caps cooperatively fullyencircle portions of the corresponding crowns 128 and leave the innercircumferential stator core face 132 (cooperatively defined by thecrowns 128) exposed.

Preferably, as will be discussed in greater detail below, at least partof each yoke portion 174 preferably extends axially in such a manner asto restrict radially outward movement of the coils 118. Furthermore, theat least part of each of the crown portions 178 preferably extendsaxially in such a manner as to restrict radially inward movement of thecoils 118. As best shown in FIGS. 11 and 12, for instance, each crownportion 178 preferably includes a flared edge portion 180 supportedrelative to the stator core 116 by axially opposed struts 182. Thus, theend caps 144 preferably function both to insulate the stator core 116and to assist in management of the wiring 117.

In a preferred embodiment, interengaging structure 184 is provided atthe juncture 172 to secure and position corresponding end caps 144relative to each other. More particularly, in a preferred embodiment andas best illustrated in FIGS. 13 and 14, each end cap 144 includes anaxially projecting constricted tab 186 and an axially extending recess188. The tab 186 of a first one of a corresponding pair of end caps 144is received in the recess 188 of the second one of the correspondingpair, while the tab 186 of the second one of the pair is received in therecess 188 of the first one. Other means of securing and/or positioningthe end caps are permissible, however. For instance, latches oradhesives might be used.

Variations from the above-described general end cap 144 structure arealso permissible according to some aspects of the present invention. Forinstance, the juncture between corresponding end cap pairs may bediscontinuous, with a portion of the core thereby being exposed. It isalso permissible according to some aspects of the present invention forthe end caps to be non-discrete or for insulation to be provided by aplurality of multi-tooth end caps or coverings. Yet further, as will bediscussed in greater detail below, entirely different forms of statorcore insulation (e.g., overmolding) may additionally or alternatively beprovided.

As noted previously, each yoke portion 174 preferably extends at leastin part axially in such a manner as to restrict radial movement of thecoils 118. More particularly, each yoke portion 174 preferably includesa generally radially and circumferentially extending base portion 190overlying at least a portion of a respective one of the upper and lowertooth faces 134 and 136 and a generally axially and circumferentiallyextending retaining wall portion 192 projecting axially from the baseportion 190 and having an axial margin 194.

As best shown in FIGS. 13, 14, 17, and 18, each yoke portion 174 furtherpreferably includes a pair of axially extending pillars 196 supportingcorresponding posts 198 that project axially beyond the axial margin194. A shoulder 200 is preferably defined between each pillar 196 andcorresponding post 198. In addition, the retaining wall portion 192preferably includes recess-defining structure 202 defining a recess 204.The functions of the pillars 196, posts 198, shoulders 200,recess-defining structures 202, and recesses 204 will be discussed ingreater detail below.

In a preferred embodiment, circumferentially adjacent ones of the endcaps 144 are spaced apart by a small gap 206. It is permissibleaccording to some aspects of the present invention, however, for one ormore circumferentially adjacent end caps to be in contact with eachother.

Preferably, the end caps 144 provide an insulative layer of at leastsixty-two thousandths (0.062) inches on the stator core 116. Morepreferably, the layer is between about sixty-five thousandths (0.065)inches and seventy-five thousandths (0.075) inches thick. Mostpreferably, the layer is about seventy thousandths (0.070) inches thick.

Stator Winding Thermal Protectors Support

In a preferred embodiment and as illustrated in FIGS. 11, 12, and 15-18,the turntable motor 100 includes at least one thermal protector assembly207. The thermal protector assembly 207 includes a thermal protector 208configured to provide signals associated with the temperature of theturntable motor 100.

In a preferred embodiment, each thermal protector 208 comprises anormally closed sensor switch that opens when the rated temperature ofthe turntable motor 100 has been exceeded proximal to the thermalprotector 208. Opening of the switch may result in automatic shut-off ofthe motor, provision of a signal that is sent to an operating system,etc., as appropriate for the particular application. However, in apreferred embodiment, the thermal switch output is not directlyconnected to the motor windings or coils 118. Rather, the output ispreferably remotely monitored (e.g., by customer control).

Preferably, the switch is self-resetting, although other switch typesmay be used without departing from the scope of the present invention.

The thermal protector assembly 207 further preferably includes a pair ofprotector brackets 210 for support and mounting of the thermalprotectors 208. More or fewer brackets 210 may be provided withoutdeparting from the scope of the present invention, however, although itis preferred that the number of brackets 210 correspond to the number ofthermal protectors 208.

Preferably, as will be discussed in greater detail below, each bracket210 is coupled to the end caps 144 so as to position the correspondingprotector 208 at least substantially adjacent the wiring 117. Mostpreferably, the bracket 210 positions the corresponding protector 208 incontact with the wiring 117.

As noted previously, the wiring 117 preferably forms a plurality ofcoils 118. The bracket 110 preferably positions the correspondingthermal protector 108 at least substantially between adjacent ones ofthe coils 118.

In a preferred embodiment, as illustrated, two (2) series-connectedthermal protectors 208 are provided to ensure sensitivity to all three(3) phases of the motor windings 117 (i.e, of the coils 118). Moreparticularly, the coils 118 preferably include A-phase, B-phase, andC-phase coils. A first one of the brackets 210 preferably positions afirst one of the thermal protectors 208 at least substantially betweenan A-phase coil 218 and an adjacent B-phase coil 218. A second one ofthe brackets 210 preferably positions a second one of the thermalprotectors 208 at least substantially between a B-phase coil 218 and anadjacent C-phase coil 218. Such an arrangement enables efficientmonitoring of the three (3) phases. However, more or fewer thermalprotectors may be provided and/or may be alternatively connected.

For instance, a thermal protector might be provided for each of thethree (3) phases (i.e., three (3) protectors total), or the thermalprotectors might be connected instead in parallel if appropriatemeasures are taken to ensure appropriate readings are taken.

Preferably, each bracket 210 includes a case 212. The case 212preferably includes a base 216 and a pair of side walls 218 extendingfrom the base 216. The case 212 further preferably includes a pair ofside hooks 220 extending from the base 216 between the side walls 218.The base 216, the side walls 218, and the side hooks 220 cooperativelyat least in part surround, engage, and retain the thermal protector 208.

More particularly, each thermal protector 208 preferably includes asensor 213 and a sleeve 214 encircling or at least in part surroundingthe sensor 213. The base 216, the side walls 218, and the side hooks 220preferably cooperatively in part surround the sensor 213 and directlyengage the sleeve 214. A variety of means of supporting the protectorare permissible, however.

The case 212 also preferably includes a resiliently deflectable springarm 222 providing an axial retention force on the protector 208. Thatis, the spring arm 22 preferably yieldably engages the protector 208 soas to restrict shifting thereof. However, omission of the spring arm isallowable according to some aspects of the present invention.

As discussed in greater detail below, the bracket 210 preferablyadditionally aids in appropriate positioning of the respective protector208. Provision of a such a means of both securely supporting andaccurately positioning the protector 208 is highly advantageous,enabling greater ease of assembly of the stator 112, more repeatablepositioning of the protector 208, and acquisition of more accuratethermal data from the wiring 117 (or from specific ones of the coils118) by the thermal protector 208.

In keeping with the above-described positioning functionality, the case212 preferably includes a mounting portion 224 including a mountingplate 226 and a pair of resiliently deflectable fingers or latches 228extending from the mounting plate 226. More particularly, the mountingplate 226 preferably extends generally radially outwardly, while thelatches 228 preferably extend generally axially.

In a preferred embodiment, a plurality of post-receiving openings 230are formed in each of the mounting plates 226. The post-receivingopenings 230 correspond with the previously described pillars 196 andposts 198 of a corresponding pair of adjacent end caps 144. Moreparticularly, in a preferred embodiment, the four (4) total posts 198 ofa pair of arcuately adjacent end caps 144 extend through the four (4)post-receiving openings 230 of a single bracket 210 to couple thebracket 210 and the end caps 144. It is permissible, however, for moreor fewer post-receiving openings, pillars, and posts to be provided.Furthermore, it is permissible for more or fewer end caps to beassociated with support of a single bracket. For instance, a single endcap might be provided to support a sole corresponding bracket.

As noted previously, the pillars 196 and the posts 198 preferably extendgenerally axially. The posts 198 therefore preferably restrict relativeradial and circumferential movement between the corresponding bracket210 and end caps 144.

Furthermore, as also noted previously, each pillar 196 preferablydefines a shoulder 200 adjacent the corresponding post 198. Eachshoulder 200 preferably supports the bracket and restricts axialmovement between the bracket 210 and the corresponding end cap 144.

The posts 198 are preferably heat-staked or coined into place. That is,an endmost portion 232 of each post 198 is heated such that the endmostportion 232 melts and forms a cap (not shown) that extends along themounting plate 226 and secures the mounting plate 226 in place relativeto the corresponding end caps 144.

It is permissible according to some aspects of the present invention formore or fewer posts or post-receiving openings to be provided and/or forthe posts to be non-heat-staked. For instance, only two (2) posts andpost-receiving openings might be provided, or the posts could bethreaded and secured with nuts in lieu of heat-staking.

In a preferred embodiment and as best shown in FIGS. 15, 16, and 18, thelatches 228 each include a latch arm 234 and a latch head or catch 236defining a latch cam surface 238 and a latch engagement surface 240. Thelatch cam surface 238 is preferably angled about forty-five (45)° fromaxial, while the latch engagement surface 240 is preferably orthogonalto the axial direction.

As noted previously, each end cap 144 preferably includes a retainingwall portion 192 that includes recess-defining structure 202 defining arecess 204. Each catch 236 is preferably received in a corresponding oneof the recesses 204.

More particularly, each recess-defining structure 202 preferably definesa cam surface 242 and an engagement surface 244. The cam surface 242 ispreferably angled about forty-five (45)° from axial, while theengagement surface 244 is preferably orthogonal to the axial direction.

Each latch 228 is preferably resiliently deformable in such a mannerthat, as the bracket 210 is moved axially onto the posts 198 and pillars196, engagement of the angled latch and recess-defining structure camsurfaces 238 and 242, respectively, deflects the latch arm 234 radiallyoutwardly until the head 236 of the latch 228 clears the correspondingrecess-defining structure 202 in the radially outward direction. Uponsufficient continued axial movement, the latch 228 snaps back radiallyinwardly in such a manner that the latch and recess-defining structureengagement surfaces 240 and 244, respectively, abut one another. Suchengagement restricts axially outward movement of the bracket 210relative to the corresponding end caps 144.

The bracket 210 preferably comprises an electrically insulativematerial. For instance, in a preferred embodiment, the bracket 210comprises synthetic resin. Use of other suitable materials falls withinthe ambit of the present invention, however. Furthermore, it ispreferred that the bracket 210 is an integrally formed or, moreparticularly, integrally molded body. Multi-part construction, whetherachieved via molding processes or otherwise, is also permissible,however.

Furthermore, it is particularly noted that, according to some aspects ofthe present invention, the brackets may instead be mounted to anyalternative electrically insulative covering that at least in partcovers the stator core 116. For instance, such an insulative coveringmight instead be provided by overmolding, which could, via use ofappropriate molds, provide the preferred aforementioned structures forsecure mounting of the bracket or alternative means for supporting thebracket.

Motor Shell and Endshields Overview

The turntable motor 100 preferably includes a motor shell 246. The motorshell 246 at least substantially circumscribes the stator 112 and inpart defines a motor chamber 248 that at least substantially receivesthe stator 112 and the rotor 110.

Preferably, the shell 246 is cylindrical in form, although other shapes(e.g., polygonal) are permissible according to some aspects of thepresent invention.

In a preferred embodiment, the shell 246 comprises metal. Moreparticularly, in the preferred embodiment, the shell 246 comprises castaluminum.

The shell 246 is preferably fit on the stator core 116 via aninterference fit. More particularly, as noted previously, the statorcore 116 preferably has an outer diameter of about five and four hundredninety thousandths (5.490) inches. The shell 246 preferably has an innerdiameter of about five and four hundred eighty-six thousandths (5.486)inches. The interference fit is preferably achieved via a cold pressoperation. Non-interference fits (e.g., tight fits or slip fits) fallwithin the scope of the present invention, however. The fit might alsoalternatively be achieved via a hot drop operation.

As shown in FIGS. 3-7, in a preferred embodiment, the turntable motor100 includes a lower endshield 250 that at least substantially enclosesone end of the motor chamber 248. More particularly, as shown in FIG. 7,the lower endshield 250 preferably includes a cylindrical lip 252extending axially relative to an annular shoulder 254. The lip 252 ispreferably received within the shell 246, with an axial end (not shown)of the shell 246 abutting the shoulder 254. An annular overlappingregion 2564 is thus formed by the shell 246 and the lip 252.

The lower endshield 250 preferably supports the stator 112. Moreparticularly, in a preferred embodiment, the stator core 116 includes aplurality of fastener-receiving openings 258. A plurality of fasteners260 extend through at least some of the fastener-receiving openings 258and through corresponding apertures 262 in the lower endshield 250.

The turntable motor 100 further preferably includes an upper endshield264 that at least substantially encloses the other end of the motorchamber 248. More particularly, as illustrated in FIGS. 8 and 9, theupper endshield 264 preferably includes a cylindrical constricted region266 extending axially relative to an annular shoulder 268. Theconstricted region 266 is preferably received within the shell 246, withan axial end (not shown) of the shell 246 abutting the shoulder 268. Anupper annular overlapping region 270 is thus formed by the shell 246 andthe constricted region 266.

Preferably, the fit of the shell 246 and the lower and upper endshields250 and 264 is a tight fit. However, it is permissible within someaspects of the present invention for an interference fit or other typeof fit, such as a slip fit in combination with fasteners, to be used.

Motor Shaft Bearings

The turntable motor 100 preferably includes a pair of upper and lowermotor shaft bearings 272 and 274 supporting the rotor 110.

The endshield 250 preferably includes a first motor shaft bearinghousing 276 and second motor shaft bearing housing (not shown)supporting the upper and lower motor shaft bearings 272 and 274,respectively and, in turn, the rotor 110. Each motor shaft bearing272,274 is preferably additionally secured by means of a respective snapring 280 and 282.

Additional details of the lower and upper endshields 250 and 264,respectively are provided below.

Integrated Endshield and Connection Box

In a preferred embodiment, the turntable motor 100 includes a connectionbox 284 that houses a motor encoder 286. In a preferred embodiment, theencoder 286 senses the position and speed of the rotor 110. Theconnection box 284 further preferably defines a pair of apertures 288and 290 in communication with connectors 292 and 294. The connection box284 further preferably covers a free end 296 of the motor shaft 154.

The connection box 284 preferably broadly includes a base wall 298, acover 300, and a side wall 302 extending between and connecting the basewall 298 and the cover 300. The apertures 288 and 290 are preferablyformed through the side wall 302.

The connection box 284 preferably includes a platform 304 on which theencoder 286 is secured using fasteners 306. Preferably, an encoder hub308 is formed in the encoder 286. The encoder 286 is mounted on theplatform in such a manner that the motor shaft 154 extends through theencoder hub 308.

An access opening 310 is preferably formed through the base wall 298 toenable access to the encoder 286. Furthermore, the cover 300 ispreferably removable from the side wall 302. More particularly, thecover 300 is preferably removably mounted to the side wall 302 usingfasteners 312, although other connection means (e.g., adhesives orlatches) may be used according to some aspects of the present invention.

The connectors 292 and 294 preferably enable the routing and connectionof wiring from the turntable motor 100 to an external device. Forinstance, in a preferred embodiment, the connectors 292 and 294 areassociated with power and with sensors and controls. The connection box284 protects the wiring from moisture and/or other contaminants.

In a preferred embodiment, each connector 292 and 294 has a threaded end314 or 316, respectively, to which a desired structure may be connected.

The connectors 292 and 294 are preferably elbow-shaped, although othershapes are permissible.

The connectors 292 and 294 are preferably secured to the connection box284 using discrete fasteners, although other connection means (e.g.,integral formation, adhesives, or latches) are permissible withoutdeparting from the scope of the present invention.

In a preferred embodiment, the connection box 284 and the lowerendshield 250 are integrally formed. More particularly, the connectionbox 284 and the lower endshield 250 are preferably formed of a singlecast aluminum structure. It is permissible according to some aspects ofthe present invention, however, for the connection box and endshield tobe discrete components connected to each other by means of fasteners,adhesives, welding, latches, or other means known in the art. Yetfurther, it is within the ambit of some aspects of the present inventionfor the endshield and connection box to be non-interconnected or onlyindirectly connected.

In a preferred embodiment, the lower endshield 250/connection box 284further preferably includes a pair of radially extending screw-on tabs318, shown in FIG. 7, and a pair of axially extending latches 320 thatrestrict rotation of corresponding ones of the tabs 318. The tabs 318preferably overhang the outer race of the lower motor shaft bearing 274.

Gearbox Assembly Overview

As noted previously, the turntable motor 100 preferably includes agearbox assembly 114. The gearbox assembly 114 preferably includes agearbox housing 322 defining a gear chamber 324 in which a gear systemor assembly 326 is substantially located.

As will be discussed in greater detail below, the gear assembly 326includes a plurality of gears received in the gear chamber 324.Furthermore, as will also be discussed in greater detail below, thehousing 322 is preferably configured to contain gear lubricant withinthe gear chamber.

In a preferred embodiment, the gear assembly 326 has a gear ratio of10:1. The gear assembly 326 preferably has an efficiency of at leastseventy-five percent (75%) and, more preferably, of at least eightypercent (80%). Most preferably, the gear assembly 326 efficiency isabout eighty-four and six tenths percent (84.6%).

As shown in FIGS. 3-6 and 8-10, the gearbox housing 322 preferablyincludes a plurality of adjoining housing portions. Most preferably, aswill be described in greater detail below, the housing 322 includes anupper portion 328, a lower portion 330, and a middle portion 332positioned between and abutting the upper and lower portions 328 and330, respectively.

In a preferred embodiment, each portion 328,330,332 of the gearboxhousing 322 is an integrally formed aluminum casting. However, it ispermissible according to some aspects of the present invention foralternative materials or formation techniques to be used. The gearboxhousing 322 could be in whole or in part machined, for instance, orformed of a different metal, such as iron.

It is also permissible according to some aspects of the presentinvention for the housing to be formed of a single piece or to includemore or fewer portions than the three (3) preferred portions describedabove. For instance, the middle portion might be formed of multiplesections rather than being integrally formed, as preferred.

In a preferred embodiment, the lower portion 330 of the gearbox housing322 is integrally formed with the upper endshield 264. Moreparticularly, the lower portion 330 and the upper endshield 264 arepreferably formed of a single cast aluminum structure. It is permissibleaccording to some aspects of the present invention, however, for thelower portion and upper endshield to be discrete components connected toeach other by means of fasteners, adhesives, welding, latches, or othermeans known in the art. Yet further, it is within the ambit of someaspects of the present invention for the endshield and lower portion tobe non-interconnected or only indirectly connected.

Preferably, the upper portion 328 of the gearbox housing 322 includes aplurality of mounting bosses 334 to enable mounting of the turntablemotor 100 to the platform 14. Other mounting means fall within the scopeof the present invention, however.

In a preferred embodiment, and as best shown in FIGS. 8-10, an O-ring336 circumscribes the upper motor shaft bearing 272 to provide a sealtherewith. More particularly, the upper motor shaft bearing 272preferably includes contact seals (e.g., rather than shields) that forma seal with the O-ring 336 to restrict ingress of lubricants (e.g., oilor grease) or other contaminants from the gear assembly 326 and gearchamber 324 into the motor chamber 248. Other bearing sealconfigurations are permissible according to some aspects of the presentinvention, however.

A wavy washer (i.e., a spring washer) 338 is preferably positioned inthe upper motor shaft bearing housing 276 between the upper motor shaftbearing 272 and a shoulder 340 formed in the upper motor shaft bearinghousing 276. The wavy washer 338 thereby preferably aids in axialpositioning of the upper motor shaft bearing 272 through cooperationwith the upper motor shaft bearing housing 276 itself and theaforementioned snap ring 280.

In a preferred embodiment, the upper endshield 264 defines an inputsealing chamber 342 adjacent the upper motor shaft bearing 272. Themotor shaft 154 preferably extends through the input sealing chamber 342and presents a smooth outer surface 334 therein.

Shaft Sleeve Providing Seal-Engaging Surface

The input sealing chamber 342 preferably houses a motor shaft sleeve orsealing sleeve 346 that at least substantially (most preferablycompletely) circumscribes the motor shaft 154 and an input seal 348 thatat least substantially (most preferably completely) circumscribes thesealing sleeve 346. As will be discussed in greater detail below, theseal 348 is preferably configured to restrict passage of contaminantsbetween the gear chamber 324 and the motor chamber 248.

Preferably, both the sleeve 346 and the input seal 348 extend at leastsubstantially continuously circumferentially, although discontinuitiessuch as holes or slits are permissible according to some aspects of thepresent invention.

As will be discussed in greater detail below, the sealing sleeve 346 ispreferably fixed to the motor shaft 154 to rotate therewith. That is,the sleeve 346 preferably rotates with the shaft 154 and is axiallyfixed to the shaft 154 to maintain its position along the shaft 154.

In a preferred embodiment, the sealing sleeve 346 presents oppositeaxial ends 346 a,346 b and an outer sleeve surface 346 c extendingbetween the ends 346 a,346 b. The sealing sleeve 346 further preferablydefines an outer seal-engaging surface 350 along the outer sleevesurface 346 c.

The input seal 348 preferably presents presenting an inner seal surface351 that sealingly engages the seal-engaging surface 350 of the sleeve346. The input seal 348 and the O-ring 336 thereby preferably bothprevent grease and/or other contaminants from the gearbox assembly 114from migrating into the motor chamber 248, with the input seal 348providing primary sealing and the O-ring 336 providing secondary orredundant sealing.

In a preferred embodiment, the upper end 352 of the motor shaft 154 is apinion end comprising a toothed portion 354. The toothed portion 354preferably presents a plurality of teeth 354 a and has a toothed portionouter diameter. The teeth 354 a are preferably helical teeth, asillustrated, although other tooth types are permissible according tosome aspects of the present invention.

The motor shaft 154 preferably presents a smooth portion 355 adjacentthe toothed portion 354. The smooth portion 355 preferably presents asmooth portion outer diameter that is at least substantially equal tothe toothed portion outer diameter.

In a preferred embodiment, the toothed portion 354 includes a transitionregion 355 adjacent the smooth portion 355. The transition region 355 ispreferably defined by a “sweep out” or other form of transition betweensmoothed and toothed surfaces.

The sealing sleeve 346 preferably at least substantially circumscribesthe shaft 154 along the smooth portion 355. The sealing sleeve 346thereby presents an inner diameter that is at least substantially equalto (i.e., slightly larger than) both the toothed portion outer diameterand the smooth portion outer diameter, as well as an outer sleevesurface outer diameter that is larger than both the toothed portionouter diameter and the smooth portion outer diameter.

The outer sleeve surface 346 c preferably has an at least substantiallyconstant sleeve outer diameter from one end 346 a of the sleeve to theother end 346 b, such that seal-engaging surface 350 has an outerdiameter at least substantially equal to that of the remainder of theouter sleeve surface 346 c. Thus, the seal-engaging surface outerdiameter is likewise larger than both the toothed portion outer diameterand the smooth portion outer diameter.

Provision of the sealing sleeve 346 between the motor shaft 154 and theinput seal 348 preferably enables assembly of the turntable motor 100without damage occurring to the input seal 348. That is, the teeth 354 acould cause cuts, abrasion, or other damage to the input seal 348 duringmotor shaft 154 insertion if the protective sealing sleeve 346 were notplaced on the motor shaft 154.

More particularly, due to the aforementioned relative diametrical sizingof the sleeve 346 (relative to the toothed portion 354) and theengagement of the input seal 348 and the sleeve 346, the inner sealsurface 351 necessarily presents a seal inner diameter that is greaterthan the toothed portion outer diameter. If the sleeve were not present,the seal would be sized to have a much smaller diameter in order toengage the smooth outer surface of the motor shaft. The seal wouldtherefore be at great risk of damage by the teeth, which have an outerdiameter identical to or nearly identical to that of the smooth outersurface of the motor shaft.

Preferably, the sealing sleeve 346 is discrete from the motor shaft 154.Most preferably, the sleeve 346 is fixed to the motor shaft 154 via athermal fit. However, it is within the scope of some aspects of thepresent invention for other types of interference fit or, more broadly,other fixation types in general, to be used. Furthermore, it ispermissible according to some aspects of the present invention for thesealing sleeve 346 to be integrally formed with the motor shaft 154.

In a preferred embodiment, the input seal 348 is a double-lip sealincluding a spring 348 a that provides additional securement forces.Other types of seals are permissible, however.

Preferably, the O-ring 336 and the input seal 348 each comprise acompressible material suitable for sealing purposes. For instance, in apreferred embodiment, the O-ring 336 comprises nitrile, and the inputseal 348 comprises a fluoroelastomer such as Viton®.

The sealing sleeve 346 preferably comprises a metal or resilientmaterial. More particularly, in a preferred embodiment, the sealingsleeve 346 comprises steel. The steel is preferably carbon steel. Mostpreferably, for instance, the sealing sleeve 346 comprises 1215 steelor, alternatively, 1018 or 1144 steel.

The steel forming the sealing sleeve 346 is preferably hardened and ismost preferably carburized. Non-hardened steel or alternatively hardenedsteel may be used without departing from some aspects of the presentinvention, however.

The sealing sleeve 346 is preferably at least in part machined. Moreparticularly, the sealing sleeve 346 is preferably polished to improvethe surface finish of at least the outer seal-engaging surface 350 (andmost preferably the entire outer sleeve surface 346 c) to enable a goodseal to be formed between the outer seal-engaging surface 350 and theinput seal 348.

Preferably, the motor shaft 154 is formed of 8620 steel that ismachined, then hardened by both carburizing and induction hardening.

A second preferred sealing sleeve embodiment is shown in FIG. 10a . Itis initially noted that, with the certain exceptions discussed below,many features of the sealing sleeve and related components of the secondembodiment are the same as or very similar to those described in detailabove in relation to the sealing sleeve 346 and related components ofthe first embodiment. Therefore, for the sake of brevity and clarity,redundant descriptions and numbering are generally avoided here. Unlessotherwise specified, the detailed descriptions of the elements presentedabove with respect to the first embodiment should therefore beunderstood to apply at least generally to the second embodiment, aswell.

In the illustrated first preferred embodiment best shown in FIGS. 8-10,the sealing sleeve 346 circumscribes the motor shaft 154 along only thesmooth portion 355. In an alternative embodiment illustrated in FIG. 10a, however, an alternative sealing sleeve 1110 extends axially in such amanner as to at least substantially circumscribe a motor shaft 1112along both a smooth portion 1114 thereof and a toothed portion 1116thereof.

Yet further, the sleeve 1110 extends axially over a transition region1118 of the toothed portion 1116. The transition region 1118 ispreferably a region of the toothed portion 1116 immediately adjacent thesmooth portion 1114 and is similar to the transition region 356described above with respect to the first preferred embodiment.

It is also permissible, but not illustrated, for a sealing sleeve to beprovided that circumscribes the motor shaft along only a transitionregion thereof, only along a toothed portion thereof, along only acombination of a smooth portion and the transition region thereof, oralong only a combination of the transition region and toothed portion.

In the preferred alternative embodiment shown in FIG. 10a , a seal 1120engages the sleeve adjacent (i.e., radially outside) the smooth portion1114. However, it is permissible for the seal 1120 to additionally oralternatively engage the sleeve adjacent the transition region and/orthe toothed region.

Sealed Housing of Gearbox Assembly

As noted previously and as shown in FIGS. 3-6 and 8-10, the gearboxhousing 322 preferably includes the upper portion 328, the lower portion330, and the middle portion 332 abutting the upper and lower portions328,330.

In a preferred embodiment, the middle housing portion abuts the upperand lower housing portions along respective upper and lower interfaces332 a,332 b exposed to the gear chamber 324.

In a preferred embodiment, the gear chamber 324 includes an upperchamber 358 defined by the upper and middle portions 328 and 332 of thegearbox housing 322. The gear chamber 324 also includes a lower chamber360 defined by the middle and lower portions 332 and 330 of the gearboxhousing 322. Because the upper and middle portions 328 and 332 definethe upper chamber 358, the upper interface 332 a is preferably exposedto the upper chamber 358. Similarly, the lower interface 332 b ispreferably exposed to the lower chamber 360.

Preferably, the upper chamber 358 and the lower chamber 360 are at leastpartly and, most preferably, at least substantially fluidly sealedrelative to each other by means that will be discussed in greater detailbelow.

In a preferred embodiment, an upper seal 362 is preferably positionedalong the interface 332 a between the upper and middle portions 328 and332. Furthermore, the chamber 358 is configured so that a lubricantfill-line is below the interface 332 a and therefore the seal 362. Theupper seal 362 preferably at least substantially (and preferablycontinuously) circumscribes the gear chamber 324 (more particularly, theupper chamber 358) and at least substantially prevents leakage oflubricants from the upper chamber 358 through the interface 332 a.

Similarly, a lower seal 364 is preferably provided preferably positionedalong the interface 332 b between the middle and lower portions 332 and330, above a lubricant fill-line of the lower chamber 360. The lowerseal 364 preferably at least substantially (and preferably continuously)circumscribes the gear chamber 324 (more particularly, the lower chamber360) and at least substantially prevents leakage of lubricants from thelower chamber 360 through the interface 332 b.

Each of the seals 362 and 364 preferably comprises an O-ring, althoughother seal configurations are permissible according to some aspects ofthe present invention.

In a preferred embodiment, the gearbox housing 322 defines a secondaryfill chamber or overflow chamber 366 adjacent the lower interface 332 b,such that the lower interface 332 b and the lower seal 364 are disposedbetween the gear chamber 324 and the overflow chamber 366. Moreparticularly, the lower interface 332 b and the lower seal 364 arepreferably disposed between the overflow chamber 366 and the lowerportion 330 of the gear chamber 324.

As best shown in FIG. 6, the overflow chamber 366 is preferablycooperatively defined by the lower and middle portions 330,332 of thegearbox housing 322, such that the overflow chamber 366 is defined atleast in part radially outside and below the lower interface 332 b andthe lower seal 364. More particularly, the overflow chamber 366 ispreferably largely defined by the lower portion 330, with the middleportion 332 serving primarily as a cover for the overflow chamber 366.

Preferably, the overflow chamber 366 has a generally elongated form andextends generally perimetrically around at least part of the gearchamber 324. However, as best shown in FIG. 6, the overflow chamberpreferably extends along only a part of the fully circumferential lowerseal 364. That is, complete circumscription is not necessary. In apreferred embodiment, for instance, the overflow chamber 366 extendsalong only three (3) sides of the gear chamber 324 to define a generallyU-shaped or C-shaped cross-section.

The overflow chamber 366 is thus operable to retain oil or otherlubricants or contaminants escaping through the lower interface 332 band past the lower seal 364 (at least along the length of the overflowchamber 366), thereby providing an additional means of preventingleakage to ambient.

It is particularly noted that, although the above-described three-parthousing 322 associated with dual interfaces 332 a,332 b and dual seals362,364 is preferred, it is wholly within the scope of the presentinvention for more or fewer housing portions, interfaces, and seals tobe provided. For instance, an overflow chamber might suitably beprovided adjacent a single interface and seal associated with a housinghaving only an upper portion and a lower portion abutting each otheralong said interface (i.e., a housing having no middle portion). Inanother alternative, the overflow chamber might be provided adjacent anupper or intermediate interface rather than a lowermost interface; or aplurality of overflow chambers associated with a corresponding pluralityof interfaces might be provided.

Yet further, the overflow chamber might be discontinuous in form. Forinstance, a first part of the chamber might extend along a first portionof a given interface, while a second, non-interconnected part of thechamber might extend along a second portion of a given interface.

Gear Assembly Overview

In a preferred embodiment and as best shown in FIGS. 6 and 8-10, thegear assembly 326 includes an input portion 368, an intermediate portion370, and an output portion 372. Each of the portions 368,370,372 ispreferably generally axially arranged relative to a corresponding localaxis, although non-axially aligned arrangements may in some instances bepermissible.

The input portion 368 preferably includes the motor shaft 154, rotatableabout an input axis, and the toothed portion or pinion 354 formed at theend of the motor shaft 154.

The intermediate portion 370 preferably includes an intermediate shaft374 rotatable about an intermediate axis and, in axial order from bottomto top (as noted previously, directional references made herein are usedsolely for the sake of convenience and should be understood only inrelation to each other), a snap ring 376, a lower intermediate gear 378and an associated key 380, a lower intermediate transmission bearing 382rotatably supporting the intermediate shaft 374, an upper intermediategear 384, an upper intermediate transmission bearing 386 rotatablysupporting the intermediate shaft 374, and a resiliently deflectablespring element 388.

The output portion 372 preferably includes an output shaft 390 rotatableabout an output axis and, in axial order from bottom to top, a loweroutput transmission bearing 392 rotatably supporting the output shaft390, a lower output gear 394, an upper output transmission bearing 396rotatably supporting the output shaft 390, an output seal 398 and anoutput shaft nut 400, an output connector 402 and associated key 404,and a snap ring 406.

Furthermore, as will be apparent from the below detailed descriptions,the input, intermediate, and output portions 368, 370, and 372,respectively, additionally include corresponding portions of the housing322.

In a preferred embodiment, as will be discussed in greater detail below,the pinion 354 rotatably engages the lower intermediate gear 378 in thelower chamber 360 of the gear chamber 324 and drives rotation of theintermediate shaft 374. (The motor shaft 154 may therefore alternativelybe referred to as an input drive shaft.) The upper intermediate gear 384preferably rotatably engages the lower output gear 394 in the upperchamber 358 of the gear chamber 324, such that the intermediate shaft374 in turn drives the output shaft 390.

Preferably, the motor shaft 154, the intermediate shaft 374, and theoutput shaft 390 are each arranged in parallel to each other, such thatthe gear assembly 326 is a parallel-shaft gear assembly. That is, therotational axes of the shafts 154, 374, and 390 are preferably at leastsubstantially parallel. Non-parallel arrangements or partially parallelarrangements fall within the scope of some aspects of the presentinvention, however.

As will be apparent to one of ordinary skill in the art, the gearassembly 326 is preferably a multi-stage system and, most preferably, atwo-stage system. More particularly, the gear assembly includes a firststage 326 a comprising the gears 354 and 374, as well as a second stage326 b comprising the gears 384 and 394.

Shimless Gear Assembly: Intermediate Portion

As noted previously, in a preferred embodiment, the pinion 354preferably rotatably engages the lower intermediate gear 378. The lowerintermediate gear 378 is preferably secured to the intermediate shaft374 via the key 380 so as to rotate with the intermediate shaft 374,such that rotation of the pinion 354 drives rotation of both the lowerintermediate gear 378 and the intermediate shaft 374.

The snap-ring 376 preferably restricts axially downward movement (e.g.,due to gravity in certain motor orientations) of the lower intermediategear 378 relative to the intermediate shaft 374.

The middle portion 332 of the gearbox housing 322 preferably defines alower intermediate transmission bearing housing 408 including an annularmiddle housing intermediate shoulder 140. The lower intermediatetransmission bearing 382 is preferably received by the lowerintermediate transmission bearing housing 408 in such a manner as torest on the middle housing intermediate shoulder 410, best shown inFIGS. 9 and 10. More particularly, the lower intermediate transmissionbearing 382 preferably presents opposite, axially spaced apart upper andlower faces 412 and 414, respectively. The lower face 414 preferablyrests on the middle housing intermediate shoulder 410, such that themiddle housing intermediate shoulder 410 restricts axially downwardmotion (e.g., due to gravity in certain motor orientations) of the lowerintermediate transmission bearing 382.

Furthermore, as also best shown in FIGS. 9 and 10, the lowerintermediate gear 378 preferably presents an upper shoulder or contactsurface 416 that abuts the lower face 414 of the lower intermediatetransmission bearing 382 such that axially shifting of the intermediateshaft 374 and the lower intermediate gear 378 in an axially upwarddirection is restricted.

The intermediate shaft 374 preferably integrally defines acircumferential lower intermediate shaft shoulder 418, shown in FIGS. 9and 10, that abuts the upper face 412 of the lower intermediatetransmission bearing 382. The lower intermediate transmission bearing382, by nature of the support provided by the middle housingintermediate shoulder 410, thus prevents axially downward shifting(e.g., due to gravity in certain motor orientations) of the intermediateshaft 374.

In a preferred embodiment, the upper intermediate gear 384 is preferablyaxially fixed relative with the intermediate shaft 374 and additionallysecured thereto so that the intermediate gear 284 and shaft 374 rotatetogether. Most preferably, the upper intermediate gear 284 is integrallyformed with the intermediate shaft 374. It is permissible according tosome aspects of the present invention, however, for the upperintermediate gear to be a discrete gear attached to the intermediateshaft to rotate therewith while also being axially fixed relativethereto. For instance, the upper intermediate gear could be keyed to theintermediate shaft or secured via an interference fit.

Preferably, the aforementioned lower intermediate shaft shoulder 418 isdisposed axially between the upper intermediate gear 384 and the lowerintermediate transmission bearing 382, such that axially downwardshifting of the intermediate shaft 374 and the upper intermediate gear384 is restricted.

As noted previously, the upper intermediate gear 384 preferably engagesthe lower output gear 394, such that rotation of the motor shaft 154ultimately is transferred to the lower output gear 394.

The upper portion 328 of the gearbox housing 322 preferably defines anupper intermediate transmission bearing housing 420 including an annularupper housing shoulder 422, as shown in FIGS. 8-10. Furthermore, as bestshown in FIGS. 9 and 10, the intermediate shaft 374 preferably includesan integrally formed circumferential upper intermediate shaft shoulder424. The upper intermediate transmission bearing 386 is preferablyreceived by the upper intermediate transmission bearing housing 420 insuch a manner as to rest on the upper intermediate shaft shoulder 424and be spaced from the upper housing shoulder 422. More particularly,the upper intermediate transmission bearing 386 preferably presentsopposite, axially spaced apart upper and lower faces 426 and 248,respectively. The lower face 426 preferably rests on the upperintermediate shaft shoulder 424 and is axially spaced from the upperhousing shoulder 422. The upper intermediate shaft shoulder 424restricts axially downward motion (e.g., due to gravity) of the upperintermediate transmission bearing 386.

The lower and upper intermediate transmission bearings 382 and 386,respectively, are preferably slip fit on the intermediate shaft 374.Furthermore, the lower and upper intermediate transmission bearings 382and 386, respectively, are preferably ball bearings, with the lowerintermediate transmission bearing being a sealed ball bearing, althoughother bearing types are permissible according to some aspects of thepresent invention.

Preferably, the upper intermediate gear 384 and the lower intermediategear 378 are each helical gears that cooperatively create a first loadin a generally axially upward direction.

Furthermore, in a preferred embodiment, the spring element 388 ispositioned between the upper face 428 of the upper intermediatetransmission bearing 386 and the upper housing shoulder 422. The springelement 388 acts to provide a downward axial force (i.e., a second loadacting in a direction at least substantially opposite the first load) onthe upper intermediate transmission bearing 386. This downward axialforce is then transferred to or acts upon the upper intermediate gear384 and, in turn, on other components of the intermediate portion 370.

Preferably, this second load has a greater magnitude than the firstload. That is, the downward force exerted by the spring element 388 ispreferably greater than the upward force generated by the rotation ofthe helical upper and lower intermediate gears 384 and 378,respectively.

In a broad sense, therefore, the spring element 388 functions to take upany axial slack in the intermediate portion 370 of the gear assembly 326and thereby accommodates variations in axial length and positioning thatmay occur due to allowable manufacturing tolerances.

It is also noted that additional downward loads (i.e., downward loads inaddition to the second load provided by the spring element 388) areprovided by the other components of the intermediate portion 370. Forinstance, the weight of the intermediate shaft 374 places a downwardforce on the lower intermediate transmission bearing, and so on. Thesesecondary or supplemental forces assist the second load in counteringthe first load.

In a preferred embodiment, the spring element 388 comprises a wavywasher, although other spring element types or means for yieldablyurging the intermediate portion 370 downward may be used.

In a preferred embodiment, the intermediate portion 370 of the gearassembly 326 is devoid of shims. Such a configuration is enabled by theabove-described configuration of the intermediate portion 370 of thegear assembly 326. More particularly, as described above, axialpositioning of the intermediate portion 370 in a broad sense is basedprimarily on the abutment of the lower face 414 of the lowerintermediate transmission bearing 382 on the middle housing intermediateshoulder 410 and the abutment of the lower intermediate shaft shoulder418 on the upper face 412 of the lower intermediate transmission bearing382, with the wavy washer 388 accommodating axial variations due tomanufacturing tolerances and at least substantially eliminating end play(i.e., the resultant upward axial forces during motor operation arepreferably less than the downward axial forces applied by the wavywasher 388).

Shimless Gear Assembly: Output Portion

In a preferred embodiment, the previously described first and secondloads, along with third and fourth loads to be discussed below,cooperate to at least in part reduce axial shifting of not just theintermediate portion 370 but of the input, intermediate, and outputportions 368, 370, and 372. Furthermore, in keeping with the preferredreduction in shifting of all of the portions 368, 370, and 372, it ispreferred that the gear assembly 326 as a whole is devoid of shims.

As noted previously, the upper intermediate gear 384 preferablyrotatably engages the lower output gear 394. The lower output gear 394is preferably integrally formed with the output shaft 390, such that theoutput shaft 390 rotates with the lower output gear 394. It ispermissible according to some aspects of the present invention, however,for the lower output gear to be a discrete gear attached to the outputshaft to rotate therewith while being fixed axially relative thereto.For instance, the lower output gear could be keyed to the output shaftor secured via an interference fit.

The pinion 354 and the lower output gear 394 are each preferably helicalgears that cooperatively create a fourth load in a generally axiallyupward direction.

In a preferred embodiment, the lower output gear 394 is supported by thelower output transmission bearing 392. More particularly, the middleportion 332 of the gearbox housing 322 preferably defines a lower outputtransmission bearing housing 430 including an annular middle housingoutput shoulder 432 (best shown in FIGS. 9 and 10). The lower outputtransmission bearing 392 is preferably received by the lower outputtransmission bearing housing 430 in such a manner as to rest on themiddle housing output shoulder 432. More particularly, the lower outputtransmission bearing 392 preferably presents opposite, axially spacedapart upper and lower faces 434 and 436, respectively. The lower face436 preferably rests on the middle housing output shoulder 432, suchthat the middle housing output shoulder 432 restricts axially downwardmotion (e.g., due to gravity) of the lower output transmission bearing392.

As best shown in FIGS. 9 and 10, the output shaft 390 preferablypresents integrally defined opposite, axially spaced apart upper andlower shoulders or contact surfaces 438 and 440, respectively.Preferably, the upper and lower contact surfaces 438 and 440 aredisposed on opposite axial sides of the lower output gear 394 and, insome embodiments, might alternatively be integrally formed therewith.Furthermore, the lower contact surface 440 is preferably disposedaxially between the lower output gear 394 and the lower outputtransmission bearing 434.

The lower contact surface 440 preferably abuts the upper face 434 of thelower output transmission bearing 392 (which presents the lower face 436that rests on the middle housing output shoulder 432), such that boththe lower output gear 394 and output shaft 390 are supported andrestricted from axially downward motion.

In a preferred embodiment, the upper portion 328 of the gearbox housing322 defines an upper output transmission bearing housing 442. The upperoutput transmission bearing 396 is preferably received by the upperoutput transmission bearing housing 442 and rests on the upper contactsurface 438 of the lower output gear 394. More particularly, the upperoutput transmission bearing 396 preferably presents opposite, axiallyspaced apart upper and lower faces 444 and 446, respectively (the upperface 444 including two tiers). The lower face 444 preferably rests onthe upper contact surface 438 defined by the output shaft 390.

The upper and lower output transmission bearings 396 and 392,respectively, are preferably each tapered roller bearings, althoughother bearing types are permissible according to some aspects of thepresent invention.

It is noted that, as previously discussed, the upper chamber 358 and thelower chamber 360 of the gear chamber 324 are at least partly and, mostpreferably, at least substantially fluidly sealed relative to eachother. Such restriction against fluid flow is provided in part byphysical obstructions provided by the middle housing portion 332, thesealed roller bearing 382 (i.e., the lower intermediate transmissionbearing 382), and the tapered roller bearing 392 (i.e., the lower outputtransmission bearing 392). Additional restriction is provided by use ofa higher viscosity lubricant or grease within the bearing 392 than isused in the gear chamber 324. That is, the higher viscosity grease, upontight packing into the bearing 392, effectively forms a seal againstleakage of the lower viscosity grease through the interior of thebearing 392.

The upper portion 328 of the gearbox housing 322 further preferablydefines an output sealing chamber 448. The output sealing chamber 448preferably houses the output shaft nut 400 and the output seal 398.

More particularly, as shown in FIGS. 8-10, the upper portion 328preferably defines a threaded interface 450 adjacent the sealing chamber448. The output shaft nut 400 preferably includes threads 452corresponding to the threaded interface 450. The output shaft nut 400 ispreferably threadably secured in the output sealing chamber 448 by meansof interengagement of the threads 452 with the threaded interface 450.

The output shaft nut 400 preferably circumscribes the output seal 398and forms a seal therewith. The output seal 398 preferably circumscribesthe output shaft 390 and also forms a seal therewith. That is, theoutput seal 398 preferably provides seals both with the output shaft nut400 and with the output shaft 390.

Preferably, the output seal 398 comprises a compressible materialsuitable for sealing purposes. For instance, in a preferred embodiment,the output seal 398 comprises nitrile, although Viton® and othermaterials may be used without departing from the scope of the presentinvention.

The output shaft nut 400 preferably comprises steel or an alternativemetal or other material having sufficient hardness to function asrequired.

It is permissible according to some aspects of the present invention forthe output nut and seal to be a pre-assembled unit.

In a preferred embodiment, the output shaft nut 400 presents a lowercontact face or nut face 454 that abuts the upper face 444 of the upperoutput transmission bearing 396 to apply the previously mentioned thirdload thereto in a generally axially downward direction. The third loadis then transferred to (i.e., acts upon) the lower output gear 394, etc.

Thus, the output shaft nut 400 restricts axially upward motion of theupper output transmission bearing 396. More broadly, the previouslydescribed engagements between various components of the output portion372 are such that the output shaft nut 400 additionally restrictsaxially upward shifting of the output shaft 390, the lower output gear394, and the lower output transmission bearing 392.

The output connector 402 is preferably fixed to the output shaft 390 bymeans of the key 404, as shown in FIG. 9, such that rotation of theoutput shaft 390 results in rotation of the output connector.

Furthermore, as shown in FIGS. 9 and 10, the output shaft 390 preferablydefines an annular output shaft shoulder 456. The output connector 402preferably abuts the output shaft shoulder 456.

Finally, the snap ring 406 preferably additionally secures the outputconnector 402 relative to the output shaft 390, restricting axiallyupward motion of the output connector 402 relative to the output shaft390.

Turning again to the output shaft nut 400, it is preferred that theaxial length of the threaded interface 450 of the upper portion 328 ofthe gearbox housing 322 is greater than the axial length spanned by thethreads 452 of the output shaft nut 400. Such disparity enables theoutput shaft nut 400 to be axially positioned as appropriate for axiallysecuring other components of the output portion 372 of the gear assembly326 (via transfer of axial force from the lower contact face 454 of theoutput shaft nut 400 to the upper face 444 of the upper outputtransmission bearing 396 and onward through the output portion 372).

That is, the output shaft nut 400 is shiftable to accommodate axialvariations due to manufacturing tolerances and can be torqued as desiredto achieve an appropriate third load magnitude. An appropriate thirdload magnitude results in an appropriate balance between the first,second, third, and fourth loads and, in turn, a substantial overall lackof shifting (or at least some degree of reduction in axial shifting) ofeach of the input, intermediate, and output portions 368, 370, and 372.Such lack of or reduction in shifting preferably enables the preferredshimless design not just of the intermediate portion 370 but of theoutput portion 372 and of the gear assembly 326 as a whole.

It is noted that additional downward loads (i.e., downward loads inaddition to the third load provided by the nut 400) are provided by theother components of the output portion 370. For instance, the weight ofthe output shaft 390 places a downward force on the lower outputtransmission bearing 392, and so on. These secondary or supplementalforces assist the third load in countering the fourth load.

The components of the output portion 372 are preferably “set” duringassembly by loading the nut 400 sufficiently to prevent all axialmovement of the output shaft 390. This might require the nut 400 to be“overloaded” relative to the desired third load (i.e., the downward loaddesired to counter the upward fourth load of the output portion 372). Toensure the output portion 372 is not overloaded during operation, thenut 400 is initially torqued to ensure there is no axial play in theoutput shaft 390, as described. The nut is then backed off (i.e.,loosened) and re-torqued to a predetermined amount that corresponds withthe desired third load.

Again, with respect to the output portion 372, such a configuration isenabled the by axial positioning of the output portion 372 that isachieved in a broad sense based primarily on the abutment of the lowerface 436 of the lower output transmission bearing 392 on the middlehousing output shoulder 432 and the abutment of the lower contact face440 of the lower output gear 394 (which is preferably integrally formedwith the intermediate shaft 390) on the upper face 434 of the loweroutput transmission bearing 392, with the axially adjustable outputshaft nut 400 accommodating axial variations due to manufacturingtolerances and at least substantially eliminating end play.

Thus, the motor shaft 154, intermediate shaft 374, and output shaft 390are at least substantially prevented from axially shifting relative toone another; and the gears associated with the shafts 154,374,390 aremaintained in acceptable axial alignment. Such stability and alignmentquality leads to less wear, lower noise, and a variety of otheradvantages.

Lift Motor

A preferred embodiment of the lift motor 500 is shown in detail in FIGS.19-32 c. It is initially noted that, with certain exceptions to bediscussed in detail below, many of the elements of the lift motor 500are the same as or very similar to those described in detail above inrelation to the turntable motor 100. Therefore, for the sake of brevityand clarity, redundant descriptions and numbering will be generallyavoided here. Unless otherwise specified, the detailed descriptions ofthe elements presented above with respect to the turntable motor 100should therefore be understood to apply at least generally to the liftmotor 500, as well.

In some cases, features described below with respect to the lift motor500 may also be applicable to the turntable motor 100.

In a preferred embodiment, the lift motor 500 broadly includes a rotor510 rotatable about an axis, a stator 512, a gearbox assembly 514, alift arm assembly 516, and a motor mounting assembly 518.

The lift motor 500 is preferably oriented such that the axis extendsgenerally horizontally and the mounting assembly 518 serves as a base orbottom structure. The lift arm assembly 516 is thus positioned on a sideof the lift motor 500. It is permissible, however, in connection withcertain aspects of the present invention, for the lift motor to bealternatively oriented. That is, unless otherwise specified or madeclear, the directional references made herein with regard to the liftmotor 500 (e.g., top, bottom, upper, lower, etc.) are used solely forthe sake of convenience and should be understood only in relation toeach other. For instance, a component might in practice be oriented suchthat faces referred to as “top” and “bottom” are sideways, angled,inverted, etc. relative to the chosen frame of reference.

The lift arm assembly 516 preferably indirectly engages the platform 14via a scissor mechanism (not shown) to raise and lower the platform 14.Such a configuration is not necessary, however.

Stator Overview

Similar to the stator 112 of the turntable motor 100 and as shown inFIGS. 22 and 29, the stator 512 of the lift motor 500 preferablyincludes a generally toroidal stator core 520 and a plurality of coils522 wound about the stator core 520. The coils 522 preferably compriseelectrically conductive wiring 524.

The stator core 520 preferably has an axial length of about one andtwenty-five hundredths (1.25) inches, an outside diameter of about fiveand four hundred ninety thousandths (5.490) inches, and an insidediameter of about three and two hundred thirty-four (3.234) inches.

Furthermore, the stator core 520 is preferably electrically insulated bymeans of electrically insulative end caps 526.

In a preferred embodiment, the lift motor 500 includes at least onethermal protector 528 secured to the end caps 526 and configured toprovide signals associated with the temperature of the lift motor 500.

The stator core 520 preferably includes twelve (12) teeth 530 definingtwelve (12) slots 532 therebetween.

Rotor Overview

As shown in FIG. 29, the rotor 510 preferably includes a rotor core 534,a plurality of arcuately arranged magnets 536, and a motor shaft 538.

The magnets 536 are preferably generally secured as described above withrespect to the magnets 152 of the turntable motor 100. However, themagnet retention means must be sufficient only to restrict magnetdislodgement at all speeds of the lift motor 500 rather than those ofthe turntable motor 100. In a preferred embodiment, for instance, thelift motor 500 has a high speed of about eight hundred forty (840) rpmand a maximum speed of about eight hundred forty (840) rpm. Such speeds,in combination with a preferred mass of the magnets 536 of abouttwenty-three and six tenths (23.6) grams each and the radial positioningof the magnets 536 relative to the axis of rotation, lead to centrifugalmagnet forces of about one and fifty-four hundredths (1.54) lb. Themagnets 536 may also be subject to radial forces of about fifty-five andsix tenths (55.6) lb due to the maximum motor torque force of aboutfifty-five and seven tenths (55.7) lb (i.e., about thirteen and ninetenths (13.9) lb/magnet, wherein the radial magnetic force isapproximately four (4) times the torque force).

The magnet retention means should also be sufficient to restrict magnetdislodgement at all possible magnet temperatures during operation of thelift motor 500. In a preferred embodiment, for instance, the magnetretention means function acceptably when the magnets 536 are attemperatures between about zero degrees Celsius (0° C.) and a predictedmaximum temperature of about sixty-one and two tenths degrees Celsius(61.2° C.).

The magnets 536 are preferably rare earth magnets. More particularly,the magnets 536 are preferably thirty-five (35) uh (one hundred eightydegrees Celsius (180° C.)) grade neodymium iron boron magnets. Othermagnet types may be used without departing from some aspects of thepresent invention, however. For instance, the magnets might be of alower grade and/or comprise ferrite.

In a preferred embodiment, eight (8) magnets 536 are provided and defineeight (8) poles. Similar to the turntable motor 100, the lift motor 500is therefore preferably a twelve (12) slot, eight (8) pole motor.

Each magnet 536 is preferably about one and twenty-five hundredths(1.25) inches in length and extends along an arc of about thirty-two(32)°.

The rotor core 534 preferably has an axial length of about one andtwenty-five hundredths (1.25) inches.

Motor Shell and Endshields Overview

The lift motor 500 further preferably includes a motor shell 540 atleast substantially circumscribing the stator 512 and in part defining amotor chamber 542 that at least substantially receives the stator 512and the rotor 510.

In a preferred embodiment, the lift motor 500 includes a first sideendshield 544 that at least substantially encloses one end of the motorchamber 542 and a second side endshield 546 that at least substantiallyencloses the other end of the motor chamber 542. The first and secondside endshields 544 and 546, respectively, will be discussed in greaterdetail below.

Connection Box

The lift motor 500 further preferably includes a connection box 548configured similarly to the connection box 284 of the turntable motor100. For instance, in a preferred embodiment, the connection box 548 isin part integrally formed with the first side endshield 544.Furthermore, the connection box 548 preferably comprises includes a basewall 550, a cover 552, and a side wall 554 extending between andconnecting the base wall 550 and the cover 552.

As best shown in FIG. 22, the connection box 548 preferably houses amotor encoder (not illustrated but similar to the encoder 286 of theturntable motor 100) and provides a pair of apertures 556 and 558 incommunication with connectors 560 and 562. The connection box 548further preferably substantially covers a free end 564 of the motorshaft 538 and protects wiring 566 extending between the lift motor 500and an external device via the connectors 560 and 562. In a preferredembodiment, for instance, the side wall 554 includes an overhangingportion 568 that extends above the wiring 566 and the encoder to protectthem from drips or other forms of contamination.

Furthermore, as shown in FIGS. 21 and 31, a portal 570 is preferablyformed in the cover 552 to enable easy access to the free end 564 of themotor shaft 538. More particularly, the free end 564 of the motor shaft538 includes a hexagonal interface 572 (best illustrated in FIG. 22)that enables a user to manually turn the motor shaft 538 if it becomeslocked (e.g., due to overloading). That is, the portal 570 enables auser to manually back up the lift motor 500 if, for example, a load werestuck in an undesirable position. Although the cover 552 could beremoved entirely to enable the necessary access, such removal would betime-consuming and potentially allow for contamination of the componentshoused by the connection box 548. In contrast, provision of the portal570 enables efficient access to the hexagonal interface while minimizingthe risk of detrimental contamination.

Gearbox Assembly Overview

As noted previously, the lift motor 500 preferably includes a gearboxassembly 514. The gearbox assembly 514 preferably includes a gearboxhousing 574 defining a gear chamber 576 in which a gear assembly 578 issubstantially located. (The gear chamber 576 is shown in FIG. 22 withthe gear assembly 578 removed, while the gear assembly 578 is shown inFIGS. 32-32 c.)

As will be discussed in greater detail below, the gearbox housing 574itself preferably forms part of the gear assembly 578.

The gearbox housing 574 is preferably secured to the shell 540 viafasteners 580, although other securement means (e.g., latches, welding,adhesives, partial or complete integral construction, etc.) mayadditionally or alternatively be used.

The gearbox housing 574 preferably includes a motor bracket 582, a firstintermediate portion 584 adjacent the motor bracket 582, a secondintermediate portion 586 adjacent the first intermediate portion 584,and an output holder 588 adjacent the second intermediate portion 586.The first and second intermediate portions 584 and 586, respectively,are thus positioned between the motor bracket 582 and the output holder588.

Preferably, the housing portions 582,584,586,588 extend continuously andare devoid of openings therein or gaps therebetween, such that gearboxhousing 574 at least substantially encloses the gear chamber 576 andprotects it from ingress of environmental contaminants.

Gearbox Assembly: Integrated Housing and Endshield

In a preferred embodiment, the motor bracket 582 of the gearbox housing574 is integrally formed with the second side endshield 546. Moreparticularly, motor bracket 582 and the second side endshield 546 arepreferably formed of a single cast structure. For instance, in apreferred embodiment, the motor bracket 582/second side endshield 546 isa cast aluminum structure. It is permissible according to some aspectsof the present invention, however, for the motor bracket and second sideendshield to be discrete components connected to each other by means offasteners, adhesives, welding, latches, or other means known in the art.Yet further, it is within the ambit of some aspects of the presentinvention for the second side endshield and motor bracket to benon-interconnected or to comprise a different material or materials(e.g., iron)

The stator 512 is preferably supported on the motor bracket 582 viafasteners 590.

Gearbox Sealing and Lubrication Management System

In a preferred embodiment and as best shown in FIG. 32a , the secondside endshield 546/motor bracket 582 includes a motor shaft bearinghousing 592. The motor shaft bearing housing 592 preferably receives amotor shaft bearing 594 that supports the motor shaft 538 in the secondside endshield 546/motor bracket 582 of the gearbox housing 574. Themotor shaft bearing 594 is preferably a ball bearing, although otherbearing types are permissible within the ambit of the present invention.

The motor shaft bearing housing 592 preferably includes a generallyradially extending base wall 596 and a circumferential sidewall 598 thatextends axially from the base wall 596. The motor shaft 538 preferablypasses through a motor shaft opening 600 defined in the base wall 596.The sidewall 598 preferably circumscribes both the motor shaft 538 andthe motor shaft bearing 594, with the motor shaft bearing 594 beingintermediately positioned between the motor shaft 538 and the sidewall598.

In a preferred embodiment, a wavy washer 602 is provided between themotor shaft bearing 594 and the base wall 596.

As best shown in FIG. 32a , it is preferable that only a very smallclearance 604 is provided between the motor shaft 538 and the base wall596 at the motor shaft opening 600. Furthermore, the motor shaft bearing594 is preferably securely fit in the motor shaft bearing housing 592,such that few or no gaps exist (e.g., via a tight fit or an interferencefit, respectively). A labyrinth 606 is thus defined that at leastsubstantially prevents ingress of lubricants (e.g., oil or grease) orother contaminants from the gear assembly 578 into the motor chamber542, without the use of a traditional seal. Other labyrinthconfigurations or even a seal may be utilized in some aspects of thepresent invention, however.

It is noted that the preferred horizontal orientation of the lift motor500 enables the effective use of the labyrinth 606 as a sealingmechanism. For instance, in a vertically oriented motor, gravity wouldwork against a labyrinthine sealing mechanism to urge contaminants topass therethrough.

The above-described preferred method of sealing the gearbox housing 574enables sealing of the gearbox housing 574 without the use of acompressible seal (e.g., a nitrile O-ring, etc.), although compressibleseals may alternatively or additionally be used without departing fromthe spirit of some aspects of the present invention.

Gearbox Assembly: Gear Assembly

In a preferred embodiment, as shown in FIG. 32a and schematically inFIGS. 32b and 32c , the gear assembly 578 is a two (2)-stage planetarygear assembly having a first stage 608 and a second stage 610. The gearassembly preferably has an 80:1 gear ratio, with the first stage 608having a 10:1 gear ratio and the second stage 610 having an 8:1 gearratio. The gear assembly 578 is therefore preferably operable todecrease speed and increase torque.

Various individual-stage gear ratios and/or overall gear ratios arepermissible without departing from the scope of the present invention,however. Furthermore, the gear ratios of the stages might be equal, orthe second stage might have a higher gear ratio than the first stage.

The gear assembly 578 preferably achieves an efficiency of at leasteighty percent (80%). More preferably, the gear assembly has anefficiency of at least eighty-five percent (85%). Most preferably, thegear assembly efficiency is about ninety percent (90%).

As shown in FIGS. 32a and 32b , the first stage 608 preferably includesa first sun gear 612, three (3) first planetary gears 614 (only oneshown in FIG. 32a for the sake of clarity) driven by the first sun gear612, three (3) needle bearings 616 (only one shown in FIG. 32a for thesake of clarity) supporting respective ones of the first planetary gears614, and a first internal gear 618 along which the first planetary gears614 orbit the first sun gear 612. A different number of planetary gearsand needle bearings may be provided without departing from the scope ofthe present invention, however.

The first sun gear 612 is preferably integrally formed at a drive end620 of the motor shaft 538, although non-integral formation ispermissible according to some aspects of the present invention. Forinstance, the first sun gear might alternatively be press fit onto thedrive end of the motor shaft.

Preferably, the first intermediate portion 584 of the gearbox housing574 comprises the first internal gear 618, although it is permissibleaccording to some aspects of the present invention for the firstintermediate portion of the housing and the first internal gear to bediscrete components.

As best shown in FIGS. 32a and 32c , the second stage 610 preferablyincludes a second sun gear 622, three (3) second planetary gears 624(only one shown in FIG. 32a for the sake of clarity) driven by thesecond sun gear 622, three (3) needle rollers 626 (only one shown inFIG. 32a for the sake of clarity) supporting respective ones of thesecond planetary gears 624, and a second internal gear 628 along whichthe second planetary gears 624 orbit the second sun gear 622. Adifferent number of planetary gears and needle rollers may be providedwithout departing from the scope of the present invention, however.

Preferably, the second intermediate portion 586 comprises the secondinternal gear 628, although it is permissible according to some aspectsof the present invention for the second intermediate portion of thehousing and the second internal gear to be discrete components.

In a preferred embodiment and as will be discussed in greater detailbelow, the gear assembly 578 transfers rotation of the motor shaft 538to an output shaft 630. The lift arm assembly 516 is preferably attachedto the output shaft 630 via a set screw or other suitable means, suchthat rotation of the motor shaft 538 causes rotation or swinging of thelift arm assembly 516.

Preferably, as shown in FIG. 32a , rotation is transferred from thefirst stage 608 to the second stage 610 by means of a carrier 632. Moreparticularly, in a preferred embodiment, the carrier 632 includes a hub634, a plate 636 extending radially from the hub 634, and three (3)carrier pins 638 (only one shown in FIG. 32a for the sake of clarity)extending axially from the plate 636. Each of the first planetary gears614 is supported on a respective one of the carrier pins 638 by acorresponding one of the needle bearings 616, such that travel of thefirst planetary gears 614 along the first internal gear 618 (i.e.,orbiting of the first sun gear 612 by the first planetary gears 614)causes rotation of the carrier 632.

The second sun gear 622 preferably includes a connection portion 640received in the hub 634 of the carrier 632, such that rotation of thecarrier 632 causes rotation of the second sun gear 622. Theinterconnection means by which rotation is transferred from the firststage to the second stage may vary without departing from the scope ofthe present invention, however.

The first planetary gears 614 are preferably evenly arcuately spacedapart. It is permissible according to some aspects of the presentinvention, however, for the first planetary gears to be unevenly spaced.

As shown in FIG. 32a , in a preferred embodiment, the output shaft 630includes a transfer portion 642, a connection portion 644, and amid-portion 646 connecting the transfer portion 642 and the connectionportion 644. Rotation is preferably transferred from the second stage tothe connection portion 644 via the transfer portion 642. The lift armassembly 516 is preferably attached to the connection portion 644 in themanner discussed above.

More particularly, in a preferred embodiment, the transfer portion 642includes three (3) generally axially extending transfer portion pins 648(only one shown in FIG. 32a ). Each of the second planetary gears 624 issupported on a respective one of the transfer portion pins 648 by acorresponding one of the needle rollers 626, such that travel of thesecond planetary gears 624 along the second internal gear 628 (i.e., theorbiting of the second planetary gears 624 about the second sun gear622) causes rotation of the transfer portion 642 and, in turn, theconnection portion 644 and the lift arm assembly 516.

The second planetary gears 624 are preferably evenly arcuately spacedapart. It is permissible according to some aspects of the presentinvention, however, for the second planetary gears to be unevenlyspaced.

In a preferred embodiment, the gear assembly 578 further preferablyincludes the motor shaft bearing 594 that supports the motor shaft 538in the motor bracket 582 of the gearbox housing 574 (as describedpreviously); an output shaft ball bearing 650 supporting the transferportion 642 of the output shaft 630 at the juncture of the first andsecond intermediate portions 584 and 586, respectively, of the gearboxhousing 574; and an output shaft roller bearing 652 supporting themid-portion 646 in the output holder 588 of the gearbox housing 574.Other bearing types (e.g., ball, roller, etc.) and/or arrangements(e.g., different positioning) are permissible without departing from theambit of the present invention, however.

The first sun gear 612 preferably includes twelve (12) teeth and isformed of carburized chromium molybdenum steel. The first planetarygears 614 preferably each include forty-eight (48) teeth and are formedof carburized chromium molybdenum steel. The first internal gear 618preferably includes one hundred eight (108) teeth and is formed oftempered and quenched chromium molybdenum steel. Other numbers of teeth,gear materials, and hardening methods (including no hardening methods)may be used within the ambit of some aspects of the present invention,however.

The second sun gear 622 preferably includes fifteen (15) teeth and isformed of carburized chromium molybdenum steel. The second planetarygears 624 preferably each include forty-five (45) teeth and are formedof carburized chromium molybdenum steel. The second internal gear 628preferably includes one hundred five (105) teeth and is formed oftempered and quenched chromium molybdenum steel. Other numbers of teeth,gear materials, and hardening methods (including no hardening methods)may be used within the ambit of some aspects of the present invention,however.

Lift Arm Assembly: Crank Arm and Pin

In a preferred embodiment, as noted previously, the lift motor 500includes a lift arm assembly 516 operable to lift the platform 14 withassistance of a scissor mechanism or other lifting aid. However, as alsonoted previously, direct lifting of the platform 14 is permissiblewithout departing from the scope of the present invention.

In a preferred embodiment and as best illustrated in FIGS. 19-31, thelift arm assembly 516 includes a generally radially extending crank arm654 fixed to the output shaft 630 and a crank pin 656 extendinggenerally axially from the crank arm 654.

The crank arm 654 preferably comprises tempered and quenched chromiummolybdenum steel with a trivalent chromate conversion coating. Othermaterials, hardening treatments (including no hardening treatments), andsurface treatments (including no surface treatments) are permissible,however.

The crank pin 656 preferably comprises tempered and quenched chromiummolybdenum steel with a hard chromium plating. Other materials,hardening treatments (including no hardening treatments), and surfacetreatments (including no surface treatments) are permissible, however.

Material selections for the crank arm 654 and the crank pin 656 areparticularly important in view of the high loads to which the crank arm654 and crank pin 656 are subjected during operation of the lift motor500. For instance, in a preferred embodiment, the crank arm 654 and thecrank pin 656 are safely operable when associated with a ten and fivetenths (10.5) rpm output speed; six hundred seventy (670) Nm outputtorque; eight thousand, eight hundred (8,800) N radial load; andtwenty-three thousand, seven hundred fifty (23,750) radial shock load(once per cycle for five hundredths (0.05) seconds).

Preferably, the crank pin 656 is press fit into the crank arm 654,although other interconnection means (e.g., adhesives and or pins) maybe used in addition to or in lieu of the preferred press fit.

The crank arm 654 preferably includes a pivot end 658, at which thecrank arm 654 is mounted to the output shaft 630 to rotate therewith,and a lifting end 660, at which the crank pin 656 is located.

In a preferred embodiment, the crank arm 654 is shiftable between three(3) positions: an upper position, best shown in FIGS. 19-24; a lowerposition, best shown in FIGS. 25 and 26; and a home position, best shownin FIGS. 27 and 28.

The home position is preferably arcuately spaced between the upper andlower positions. More particularly, the home position is preferablylocated between the upper and lower positions but nearer the lowerposition.

In a preferred embodiment, the crank arm 654 is offset from verticalwhile in either of the upper and lower positions, while the crank armextends at least substantially vertically downward when in the homeposition. Alternate orientations are permissible according to someaspects of the present invention, however.

Lift Arm Assembly: Position Sensor System

In a preferred embodiment, and as best shown in FIGS. 30 and 31, thelift arm assembly 516 includes a position sensor system 662 including aprinted circuit board 664 and a plurality of sensors mounted on theboard 664. The sensors include an upper-position sensor 666, alower-position sensor 668, and a home-position sensor 670. A wiringconnector 672 is also mounted to the board 664.

The position sensor system 662 preferably senses when the crank arm 654is in each of the upper, lower, and home positions.

In a preferred embodiment, the printed circuit board 664 includes anFR-4 laminate base with a one (1) oz copper foil. The printed circuitboard 664 is preferably single-sided and semi-circular in shape, with aradial width of about one (1) inch and an outer diameter of about fourand seventy-five hundredths (4.75) inches. Other configurations andsizes are permissible according to some aspects of the presentinvention, however. For instance, the board could use an alternativeglass-reinforced epoxy laminate backbone, a different amount of copper,and/or have different dimensions.

The sensors 666, 668, and 670 are preferably Hall Effect sensors,although use of other sensor types is permissible according to someaspects of the present invention.

Preferably, the printed circuit board 664 includes a plurality ofarcuately spaced apart mounting holes 674. Fasteners 676 extend throughthe mounting holes 674 and into the output holder 588 to fix the printedcircuit board 664 on the gearbox housing 574. Preferably, three (3)arcuately spaced apart mounting holes 674 are provided, although otherconfigurations and numbers of mounting holes are permissible.

In a preferred embodiment, the position sensor system 662 furtherincludes a gasket 678 positioned between the printed circuit board 664and the output holder 588.

Yet further, the position sensor system 662 preferably includes aprinted circuit board cover 680 that is secured to the output holder 588in such a manner as to enclose the printed circuit board 664 and thegasket 678, thereby protecting the sensors 666, 668, and 670 fromcontamination.

The position sensor system 662 further preferably includes a magnetsystem 682. More particularly, in a preferred embodiment, a magnet array684, including a plurality of magnets 686, is positioned on the crankarm 654. The sensors 666, 668, and 670 sense the magnets 686 as thecrank arm 654 moves between the upper, lower, and home positions.

Preferably, the magnet array 684 defines three alternately oriented polepairs, wherein each pole pair is oriented generally circumferentially.

In a preferred embodiment, a magnet platform 688 is fixed to and extendsgenerally radially from the pivot end 658 of the crank arm 654. Themagnet array 684 is supported on the magnet platform 688 by a magnetcarrier 690. Thus, pivoting of the crank arm 654 results in arcuateshifting of the magnet array 684. In a preferred embodiment, forinstance, rotation of the crank arm 654 (corresponding to upwardmovement of the crank pin 656) results in downward shifting of themagnet array 684.

In a preferred embodiment, the magnet platform 688 defines a pair ofoblong fastener-receiving holes 692 having generally circumferentialmajor axes. As will be discussed in greater detail below, the oblongshape of the holes 692 enables the position of the carrier 632 and, inturn, of the magnet array 684, to be adjusted circumferentially asrequired during calibration.

The magnet platform 688 is preferably secured to the crank arm 654 via apair of fasteners 694. More particularly, as shown in FIGS. 26, 28, and29, the magnet platform 688 preferably defines an axially extending slot696 therethrough. The fasteners 694 preferably extend through the slot696 and into the crank arm 654 to secure the magnet platform 688 to thecrank arm 654. As will be discussed in greater detail below, axialextension of the slot 696 allows the magnet platform 688 and, in turn,the magnet array 684, to be adjusted axially during calibration (e.g.,moved nearer to or away from the printed circuit board cover 680 and,more particularly, the sensors 666, 668, and 670 therebelow).

In a preferred embodiment, the printed circuit board 664 is oriented insuch a manner as to present an upper end 700 and a lower end 702. Thewiring connector 672 is preferably positioned adjacent the lower end702. The upper-position sensor 666 is preferably positioned nearer thelower end 702 than the upper end 700. The lower-position sensor 668 ispreferably positioned adjacent the upper end 700. The home-positionsensor 670 is preferably positioned nearer the upper end 700 than thelower end 702.

In a preferred embodiment, the sensors 666, 668, and 670 are positionedon the printed circuit board in a radially staggered manner. Moreparticularly, in a preferred embodiment, the home-position sensor 670 ispositioned radially inwardly relative to the radially intermediatelypositioned upper-position sensor 666 and the radially outwardlypositioned lower-position sensor 668. Such positions preferably alignwith the rotational track of the magnets 686. Thus, although alternativearrangements are permissible according to some aspects of the presentinvention, such alternative arrangements should preferably enablealignment of the sensors to the magnet path to ensure accurate positionsensing.

Preferably, the magnet array 684 is calibrated to the home-positionsensor 670 during assembly of the lift motor 500. More particularly, ina preferred embodiment, the crank arm 654 is first set to the homeposition. The magnet array 684 is then shifted circumferentially andaxially (as respectively enabled by the oblong fastener-receiving holes692 and the slot 696 of the magnet platform 688) such that the magnetarray 684 is circumferentially aligned with the home-position sensor 670and separated from the printed circuit board cover 680 (and thus thesensors 666, 668, and 670) by only a very small axial air gap 705.

Lift Arm Assembly: Arm Stops

The output holder 588 preferably includes an upper arm stop 704 and alower arm stop 706 arcuately spaced away from the upper arm stop 704.The upper arm stop 704 preferably prevents the crank arm 654 fromrotating past the upper position, while the lower arm stop 706preferably prevents the crank arm 654 from rotating past the lowerposition. That is, the arm stops 704 and 706 limit swinging movement ofthe crank arm 654.

More particularly, in a preferred embodiment, the crank arm 654 presentsupper and lower stop-contacting surfaces 708 and 710, respectively. Theupper arm stop 704 presents an upper arm-contacting surface 712, and thelower arm stop 706 presents a lower arm-contacting surface 714. When thecrank arm 654 is in the upper position, the upper stop-contactingsurface 708 abuts the upper arm-contacting surface 712. When the crankarm 654 is in the lower position, the lower stop-contacting surface 710abuts the lower stop-contacting surface 714.

In a preferred embodiment, the upper and lower stops 704 and 706,respectively, are integrally formed with the output holder 588. Suchintegral formation is highly advantageous, enabling the stops 704 and706 to withstand greater forces (e.g., due to forced or driven contactwith the crank arm 654) than achieved via a conventional non-integralattachment. Non-integral configurations are permissible according tosome aspects of the present invention, however. For instance, the stopscould alternatively be bolted into place, provided the configuration isable to withstand operational shear forces.

In a preferred embodiment, the output holder 588 and upper and lowerstops 704 and 706 comprise non-heat treated ductile cast iron. Othermaterials or processes may be used without departing from some aspectsof the present invention, however. For instance, the output holder andstops might alternatively be subjected to one or more heat treatmentprocesses or comprise steel.

Motor Mounting

As noted previously, in a preferred embodiment, the lift motor 500includes a motor mounting assembly 518. The mounting assembly 518preferably includes a base plate 716 fixed to the chassis of the robot10. Furthermore, the output holder 588 preferably includes a mountingportion 718 secured to the base plate 716 and forming part of themounting assembly 518.

Sensor Wire Protection

In a preferred embodiment, the printed circuit board cover 680 includesa first wire protection extension 720, and the connection box 548includes a second wire protection extension 722. Furthermore, the baseplate 716 defines an axially extending wire protection trough 724. Thewire protection extensions 720 and 722 and the trough 724 cooperativelydefine a wiring passageway 726.

In a preferred embodiment, the wiring 566 includes sensor wiring 728extending between the printed circuit board 664 and the connection box548 (or, more particularly, from the wiring connector 672 to an externaldevice configured to receive feedback from the sensors 666, 668, and670). The sensor wiring 728 is preferably routed through the wiringpassageway 726. The extensions 720 and 722 and trough 724 serve toprotect the sensor wiring 728 from contact damage (e.g., from awarehouse employee) or exposure to contaminants such as water. Theextensions 720 and 722 and trough 724 also serve to protect a“contacter” (e.g., a warehouse employee) from the sensor wiring 728.

Preferably, the first wire protection extension 720 includes an at leastsubstantially solid rear wall 730 extending generally downwardly, andalso includes a pair of sidewalls 732 extending axially from the rearwall 730.

The second wire protection extension 722 preferably similarly includes arear wall 734 extending generally downwardly, as well as a pair ofsidewalls 736 extending axially from the rear wall 734. However, incontrast to the rear wall 730 of the first wire protection extension720, the rear wall 734 of the second wire protection extension 722preferably defines an access slot 738.

In a preferred embodiment, a barrier 740 extends generallyperpendicularly across the trough 724 to restrict upward movement of thesensor wiring 728 out of the trough 724. It is permissible, however, forthe barrier to be omitted or alternatively oriented without departingfrom the scope of some aspects of the present invention.

Preferably, the trough 727 is positioned directly below the shell 540and gearbox housing 574, such that the shell 540 and gearbox housing 574provide a physical barricade against some forms of contaminantdetrimental to the sensor wiring 728. For instance, the shell 540 andgearbox housing 574 are capable of deflecting water droplets that mightotherwise enter the trough 724 and/or contact the sensor wiring 728.

Provision of the wiring passageway 726 outside the shell 540 and thegearbox housing 574 enables decreased shell 540 and gearbox housing 574dimensions (i.e, permits the shell 540 and the gearbox housing 574 to besmaller).

In a preferred embodiment, the sensor wiring 728 is additionallyprovided with compressible seals 742 and a cable 744 particularlyconfigured to prevent water and dust ingress.

Locomotion Motor

A preferred embodiment of the locomotion motor 800 is shown in detail inFIGS. 33-46. It is initially noted that, with certain exceptions to bediscussed in detail below, many of the elements of the locomotion motor800 are the same as or very similar to those described in detail abovein relation to the turntable motor 100 and/or the lift motor 500.Therefore, for the sake of brevity and clarity, redundant descriptionsand numbering will be generally avoided here. Unless otherwisespecified, the detailed descriptions of the elements presented abovewith respect to the turntable motor 100 and the lift motor 500 shouldtherefore be understood to apply at least generally to the locomotionmotor 800, as well.

In some cases, features described below with respect to the locomotionmotor 800 may also be applicable to the turntable motor 100 and/or thelift motor 500.

In a preferred embodiment, the locomotion motor 800 broadly includes arotor 810 rotatable about an axis, a stator 812, a gearbox assembly 814,and one of the wheels 16.

The locomotion motor 800 is preferably oriented such that the axisextends generally horizontally. It is permissible, however, inconnection with certain aspects of the present invention, for thelocomotion motor to be alternatively oriented. That is, unless otherwisespecified or made clear, the directional references made herein withregard to the locomotion motor 800 (e.g., top, bottom, upper, lower,etc.) are used solely for the sake of convenience and should beunderstood only in relation to each other. For instance, a componentmight in practice be oriented such that faces referred to as “top” and“bottom” are sideways, angled, inverted, etc. relative to the chosenframe of reference.

Stator Overview

Similar to the stator 112 of the turntable motor 100 and the stator 512of the lift motor 500, the stator 812 of the locomotion motor 800preferably includes a generally toroidal stator core 816 and a pluralityof coils 818 wound about the stator core 816.

The stator core 816 preferably has an axial length of about two (2)inches, an outside diameter of about five and four hundred ninetythousandths (5.490) inches, and an inside diameter of about three andtwo hundred thirty-four thousandths (3.234) inches.

Furthermore, the stator core 816 is preferably electrically insulated bymeans of electrically insulative end caps 820.

In a preferred embodiment, the locomotion motor 800 includes at leastone thermal protector 822 secured to the end caps 820 and configured toprovide signals associated with the temperature of the locomotion motor800.

The stator core 816 preferably includes twelve (12) teeth 824 definingtwelve (12) slots 826 therebetween.

Rotor Overview

The rotor 810 preferably includes a rotor core 828, a plurality ofarcuately arranged magnets 830, and a motor shaft 832.

The magnets 830 are preferably generally secured as described above withrespect to the magnets 152 of the turntable motor 100 and the magnets536 of the lift motor 500. However, the magnet retention means must besufficient to restrict magnet dislodgement at all speeds of thelocomotion motor 800 rather than those of the turntable motor 100 or thelift motor 500. In a preferred embodiment, for instance, the locomotionmotor 800 has a high speed of about one thousand, one hundredseventy-six (1176) rpm and a maximum speed of about one thousand, onehundred seventy-six (1176) rpm. Such speeds, in combination with apreferred magnet 830 mass of about fifteen and three tenths (15.3) gramsand the radial positioning of the magnets 830 relative to the axis ofrotation, lead to centrifugal magnet forces of about four and forty-sixhundredths (4.46) lb. The magnets 830 may also be subject to radialforces of about sixty-six and eight tenths (66.8) lb due to the maximummotor torque force of about one hundred thirty-three and six tenths(133.6) lb (i.e., about sixteen and seven tenths (16.7) lb/magnet,wherein the radial magnetic force is approximately four (4) times thetorque force).

The magnet retention means should also be sufficient to restrict magnetdislodgement at all possible magnet temperatures during operation of thelocomotion motor 800. In a preferred embodiment, for instance, themagnet retention means function acceptably when the magnets 830 are attemperatures between about zero degrees Celsius (0° C.) and a predictedmaximum temperature of about eighty-two and seven tenths degrees Celsius(82.7° C.).

The magnets 830 are preferably rare earth magnets. More particularly,the magnets 830 are preferably forty-five (45) sh (one hundred fiftydegrees Celsius (150° C.)) grade neodymium iron boron magnets. Othermagnet types may be used without departing from some aspects of thepresent invention, however. For instance, the magnets might be of alower grade and/or comprise ferrite.

In a preferred embodiment, sixteen (16) magnets 830 are provided anddefine eight (8) poles. More particularly, the magnets 830 arepreferably “split magnets” for reduced eddy current loss, with eight (8)pairs of axially aligned magnets 830 being arcuately arranged about therotor core 828.

Similar to the turntable motor 100 and the lift motor 500, thelocomotion motor 800 is preferably a twelve (12) slot, eight (8) polemotor.

Preferably, each of the magnets 830 has an axial length of abouteighty-three hundredths (0.83) inches and presents an arc of aboutthirty-two degrees (32°).

The rotor core 828 preferably has an axial length of about one and sevenhundred eighty-eight thousandths (0.788) inches.

Motor Shell and End Plates Overview

The locomotion motor 800 further preferably includes a housing 833defining a motor chamber 836 that at least substantially houses thestator 812 and the rotor 810.

The housing 833 preferably includes a shell 834 at least substantiallycircumscribing the stator 812. The housing 833 also includes first andsecond side end plates 838 and 840, respectively, that connect with theshell 834 to at least substantially enclose respective ends of the motorchamber 836.

In a preferred embodiment, the first side end plate 838 includes aunitary, integrally formed end plate body 838 a. Most preferably, theend plate body 838 a is a cast body (e.g., a cast aluminum body),although other means of integral formation are permissible.

In a preferred embodiment, the first side end plate 838 at least in partdefines an electronics compartment 839. The end plate body 838 apreferably defines an access opening 839 a to the electronicscompartment 839.

Preferably, the end plate 838 includes a removable cover 842 at least inpart covering the access opening 839 a but enabling access to, amongother things, a motor encoder 844 at least in part disposed in theelectronics compartment 839, without removal of the entire first sideend plate 838. The cover can be omitted without departing from the scopeof the present invention, however.

In a preferred embodiment, the motor shell 834 includes a plurality ofradially extending fins 846 operable to disperse heat from thelocomotion motor 800. The fins 846 preferably define a generallycuboidal shell envelope, although a circular or otherwise shapedenvelope is permissible.

The motor shell 834 may be ventilated or unventilated. Preferably,however, the motor shell 834 includes a plurality of vent holes (notshown) to prevent or minimize the collection of heat at the bottom ofthe motor shell 834.

Motor Shell Interference Fit

In a preferred embodiment, the motor shell 834 is fit on the stator core816 via a thermal fit (i.e., a shrink fit). More particularly, the motorshell 834 is preferably heated, positioned about the stator core 816(e.g., the stator core 816 is dropped into place inside the motor shell834), and then actively or passively cooled. In its cooled state, theshell 834 has smaller dimensions than in its heated state, such that thetightness of the fit between the shell 834 and the stator core 816increases as the shell 834 cools.

In a preferred embodiment, the motor shell 834 is heated to five hundreddegrees Fahrenheit (500° F.), positioned about the stator core 816, thencooled. Other target temperatures may be used without departing from thescope of the present invention, however.

Preferably, the fit during the initial stages of thermal fitting process(i.e., when the shell is at an elevated temperature) is a slip fit,while that achieved after the thermal fitting process (i.e., after theshell has been cooled) is an interference fit. More particularly, in apreferred embodiment and as noted previously, the stator core 816 has anouter diameter of about five and four hundred ninety thousandths (5.490)inches, while the cooled shell 834 preferably has an inner diameter ofabout five and four hundred eighty-three thousandths (5.483) inches.

The shell 834 preferably comprises a different material than the statorcore 816, such that the stator core 816 and the shell 834 have differingcoefficients of thermal expansion. Preferably, both materials aremetals, although non-metal materials may be used within the ambit of thepresent invention.

More particularly, in a preferred embodiment, the shell 834 comprisesaluminum, while the stator core 816 comprises steel. The shell thermalexpansion coefficient is thus different from and, more particularly,greater than the stator core thermal expansion coefficient.

In a preferred embodiment, the shell 834 and stator core 816 thermalcoefficients are at least substantially constant throughout the shell834 and the stator core 816, respectively. It is permissible accordingto some aspects of the present invention, however, for materialvariations resulting in gradients or other variations in the thermalexpansion coefficients to be present.

In a preferred embodiment, the shell 834 and stator core 816 materialsand dimensions are chosen in such a manner that the shell 834 and thestator core 816 do not separate as a result of temperature fluctuationsassociated with motor operation.

It is permissible, however, for the shell 834 and stator core 816materials and dimensions to be chosen in such a manner that the shell834 may be removed from the stator core 816 upon heating of one or bothcomponents to a suitably high temperature or temperatures. For instance,the shell might be intentionally heated relative to the stator core toenable removal of the shell, or both the shell 834 and the stator coremight be heated for the same purpose. Such removability is not arequirement of some aspects of the present invention, however.

Motor Shell Secondary Retention

In preferred embodiment, secondary retention of the shell 834 and stator812 relative to one another is provided by a pair of spaced apart pins848, a retaining ring or spring clip 850, and a shoulder 852. Suchsecondary retention is beneficial to supplement the interference fit(i.e., the grip) achieved via the above-described thermal process.

More particularly, as best shown in FIGS. 36 and 44-46, each pin 848preferably extends through the shell 834 into the stator core 816.

As noted previously, the stator core 816 preferably comprises aplurality of teeth 824. Each of the teeth 824 preferably includes a yoke854. Each pin 848 preferably extends into the arcuate center of the yoke854 of one of the teeth 824. Non-centralized positioning or extensioninto another part of the stator core 816 is permissible according tosome aspects of the present invention, however.

Preferably, the stator core 816 has opposite, axially spaced apart firstand second side faces 856 and 858, respectively. In a preferredembodiment, each of the pins 848 extends through the shell 834 and intothe stator core 816 at an axial position that is offset from the axialcenter of the stator core 816. That is, each pin 848 is closer to one ofthe first and second side faces 856 and 858 than to the other of theside faces 856 and 858. Central positioning or varied positioningbetween the two pins is permissible according to some aspects of thepresent invention, however.

The pins 848 are preferably spaced apart by about one hundred eightydegrees (180°, although other spacing is permissible. Furthermore, moreor fewer pins might be provided. F)or instance, three unequallyarcuately spaced pins might be provided.

In a preferred embodiment, the shell 834 defines the aforementionedshoulder 852. The shoulder 852 preferably engages the first side face856 of the stator core 816 so as to restrict relative axial shifting ofthe stator core 816 and the shell 834.

Furthermore, the shell 834 preferably defines an annular groove 860 thatreceives the retaining ring 850. The retaining ring 850 engages thesecond side face 858 of the stator core 816 so as to further restrictrelative axial shifting of the stator core 816 and the shell 834.Although a retaining ring of the type shown is preferred, other similarretention means are suitable without departing from the scope of thepresent invention.

Although the above-described pins 848, shoulder 825, and retaining ring850 are preferably provided to supplement retention of the shell 834relative to the stator core 816, some or all of such features may beomitted without departing from the scope of the present invention.

Gearbox Assembly Overview

As noted previously, the locomotion motor 800 preferably includes agearbox assembly 814. The gearbox assembly 814 preferably includes agearbox case 862 (which is also part of the housing 833) defining a gearchamber 864 in which a gear assembly 866 is substantially located. (Thegear chamber 864 is shown in FIGS. 35 and 36 with the gear assembly 866removed. The gear assembly 866 is shown in FIG. 42a and schematically inFIG. 42b ).

As will be discussed in greater detail below, the gearbox case 862itself preferably forms part of the gear assembly 866.

The gearbox assembly 814 further preferably includes a dust cover 868(which is also preferably part of the housing 833) at leastsubstantially encompassing the gearbox case 862.

The gearbox case 862 preferably includes a motor bracket 870 and anoutput holder 872 adjacent the motor bracket 870. Preferably, the motorbracket 870 and the output holder 872 extend continuously and are devoidof openings therein or gaps therebetween, such that gearbox case 862 atleast substantially encloses the gear chamber 864.

The shell 834 preferably engages the dust cover 868 along a shell-dustcover interface 869 a to thereby at least substantially preventcontaminants passing across the shell-dust cover interface 869 a.

In a preferred embodiment and as best shown in FIGS. 35, 36, and 38, themotor bracket 870 includes a circumferentially extending outer flange874. The flange 874 is preferably disposed adjacent the shell-dust coverinterface 869 a.

More particularly, the motor shell 834 preferably defines a shoulder 876facing the dust cover 868, while the dust cover 868 defines a shoulder878 facing the motor shell 834. A groove 880 is cooperatively defined bythe shell 834 and the dust cover 868 between the respective shoulders876 and 878. The flange 874 is preferably received in the groove 880.The flange 874 thereby restricts relative axial motion of the shell 834and the dust cover 868.

The flange 874 also preferably restricts bending deformation of thelocomotion motor 800 at the shell-dust cover interface 869 a.

The flange 874 furthermore preferably defines a circumferentiallyextending outer groove 882. An O-ring or other seal 884 is preferablyreceived in the groove so as to abut the dust cover 868 and be at leastin part disposed between the flange 874 and the shell-dust coverinterface 869 a. The flange 874 and O-ring 884 thus cooperatively sealthe shell-dust cover interface 869 a.

In a preferred embodiment, the dust cover 868 preferably engages thegearbox case 862 along a dust cover-gearbox case interface 869 b tothereby at least substantially prevent contaminants passing across thedust cover-gearbox case interface 869 b. The dust cover-gearbox caseinterface 869 b will be described in greater detail below.

Gearbox Assembly: Integration of Components

In a preferred embodiment, the motor bracket 870 of the gearbox case 862is integrally formed with the second side end plate 840. Moreparticularly, the motor bracket 870 and the second side end plate 840are preferably formed of a single cast structure. It is permissibleaccording to some aspects of the present invention, however, for themotor bracket and second side end plate to be discrete componentsconnected to each other by means of fasteners, adhesives, welding,latches, or other means known in the art. Yet further, it is within theambit of some aspects of the present invention for the second side endplate and the motor bracket to be non-interconnected.

In a preferred embodiment, the motor bracket 870 of the gearbox case 862is integrally formed with the output holder 872 of the gearbox case 862.More particularly, the motor bracket 870 and the gearbox case 862 arepreferably formed of a single cast structure. It is permissibleaccording to some aspects of the present invention, however, for themotor bracket and the output holder to be discrete components connectedto each other by means of fasteners, adhesives, welding, latches, orother means known in the art. Yet further, it is within the ambit ofsome aspects of the present invention for the motor bracket to be onlyindirectly interconnected.

Therefore, in keeping with the above, it is preferred that the secondside end plate 840, the motor bracket 870, and the output holder 872 areall integrally formed.

The above-described construction of the gearbox case 862 enables adecreased axial length of the locomotion motor 800.

Gearbox Sealing and Lubrication Management System

In a preferred embodiment, the second side end plate 840/motor bracket870 includes a motor shaft bearing housing 886. The motor shaft bearinghousing 886 preferably receives a motor shaft bearing 888 (preferablybut not necessarily a ball bearing) that supports the motor shaft 832 onthe second side end plate 840/motor bracket 870 of the gearbox case 862.

The motor shaft bearing housing 886 preferably includes a generallyradially extending base wall 890 and a circumferential sidewall 892 thatextends axially from the base wall 890. The base wall 890 preferablyincludes a first tier 894 and a second tier 896. The motor shaft 832preferably passes through a shaft opening 898 defined in the base wall890. The sidewall 892 preferably circumscribes both the motor shaft 832and the motor shaft bearing 888, with the motor shaft bearing 888 beingintermediately positioned between the motor shaft 832 and the sidewall892.

In a preferred embodiment, a wavy washer 900 is provided between themotor shaft bearing 888 and the base wall 890.

Preferably, only a very small clearance 902 is provided between themotor shaft 832 and the base wall 890 at the shaft opening 898.Furthermore, the motor shaft bearing 888 is preferably securely fit inthe motor shaft bearing housing 886, such that few or no gaps (e.g, viaa tight fit or an interference fit, respectively) exist. A steppedlabyrinth 904 including a plurality of turns due in part to the tiers894 and 896 is thus defined.

The labyrinth 904 at least substantially prevents ingress of lubricants(e.g., oil or grease) or other contaminants from the gear assembly 866into the motor chamber 836, without the use of a traditional seal. Otherlabyrinth configurations and/or a seal along the interface between thegear assembly 866 and the motor chamber 836 may be utilized inaccordance with some aspects of the present invention, however. That is,although, the above-described preferred method of sealing the gearboxcase 862 enables sealing of the gearbox case 862 without the use of acompressible seal (e.g., a nitrile O-ring, etc.), compressible seals mayalternatively or additionally be used without departing from the spiritof some aspects of the present invention.

Gearbox Assembly: Gear Assembly

In a preferred embodiment and as will be discussed in greater detailbelow, the gear assembly 866 transfers rotation of the motor shaft 832to an output shaft 956 and, in turn, to the corresponding wheel 16. Thatis, rotation of the rotor 810 drives rotation of the corresponding wheel16.

In a preferred embodiment, the gear assembly 866 is a one (1)-stageplanetary gear assembly. The gear assembly preferably has a 10:1 gearratio and achieves an efficiency of at least eighty-five percent (85%).More preferably, the gear assembly has an efficiency of at least ninetypercent (90%). Most preferably, the gear assembly efficiency is aboutninety-four percent (94%). Other gear ratios and efficiencies arepermissible according to some aspects of the present invention, however.

The gear assembly 866 preferably reduces the power requirement for thelocomotion motor 800. That is, the gear assembly 866 is designed so asto assist the locomotion motor 800 in providing the required torque withless power draw and in a relatively small envelope.

More particularly, as shown in FIG. 42a and schematically in FIG. 42b ,the gear assembly 866 preferably includes a sun gear 908, three (3)planetary gears 910 (only one shown in FIG. 42a for the sake of clarity)driven by the sun gear 908, three (3) needle bearings 912 (only oneshown in FIG. 42a for the sake of clarity) supporting respective ones ofthe planetary gears 910, and an internal gear 914 along which theplanetary gears 910 orbit the sun gear 908. A different number ofplanetary gears and needle bearings may be provided without departingfrom the scope of the present invention, however.

The sun gear 908 is preferably integrally formed at a drive end 916 ofthe motor shaft 832, although non-integral formation is permissibleaccording to some aspects of the present invention. For instance, thesun gear might alternatively be press fit onto the drive end of themotor shaft.

Preferably, the output holder 872 of the gearbox case 862 comprises theinternal gear 914, although it is permissible according to some aspectsof the present invention for the intermediate portion of the housing andthe internal gear to be discrete components.

The first planetary gears 910 are preferably evenly arcuately spacedapart. It is permissible according to some aspects of the presentinvention, however, for the first planetary gears to be unevenly spaced.

In a preferred embodiment, the output shaft 956 includes a transferportion 918, a connection portion 920, and a mid-portion 922 connectingthe transfer portion 918 and the connection portion 920. Thecorresponding wheel 16 is preferably attached to the connection portion920, as will be discussed in greater detail below.

In a preferred embodiment and as best shown in FIG. 42a , the transferportion 918 includes three (3) generally axially extending transferportion pins 924 (only one shown in FIG. 42a for the sake of clarity).Each of the planetary gears 910 is supported on a respective one of thepins 924 by a corresponding one of the needle rollers 912, such thattravel of the planetary gears 910 along the internal gear 914 (i.e.,orbiting of the planetary gears 910 about the sun gear 908) causesrotation of the transfer portion 918 and, in turn, of the connectionportion 920 and the wheel 16.

In a preferred embodiment, the gear assembly 866 further preferablyincludes the previously described motor shaft bearing 888 supporting themotor shaft 832 in the motor bracket 870 of the gearbox case 862, afirst output ball bearing 926 supporting the transfer portion 918 of theoutput shaft 956, and a second output ball bearing 928 supporting themid-portion 922 of the output shaft 956. Other bearing types (e.g.,roller bearings) and/or arrangements (e.g., different positioning) arepermissible without departing from the spirit of the present invention,however.

It is noted that the integrally formed gearbox case 862 supports andpositions each of the bearings 888, 926, and 928.

The sun gear 908 preferably includes twelve (12) teeth and is formed ofcarburized chromium molybdenum steel. The planetary gears 910 preferablyeach include forty-eight (48) teeth and are formed of carburizedchromium molybdenum steel. The internal gear 914 preferably includes onehundred eight (108) teeth and is formed of tempered and quenchedchromium molybdenum steel. Other numbers of teeth, gear materials, andhardening methods (including no hardening methods) may be used withinthe ambit of some aspects of the present invention, however.

Motor Mounting

In a preferred embodiment and as best shown in FIGS. 33 and 34, the dustcover 868 and the motor shell 834 cooperatively present a pair of motormounting plates 930. The locomotion motor 800 is preferably mounted onthe chassis of the robot 10 by means of the mounting plates 930.

As shown in FIGS. 37 and 38, for instance, the dust cover 868 and themotor shell 834 present respective mounting plate halves 932 and 934interconnected by means of pegs 936.

Integrated Wire Sealing Structure

In a preferred embodiment, the locomotion motor 800 includes a pair ofelectrical cables 938 and 940 extending from the motor chamber 836 to aconnection interface 942 disposed externally relative to the motorchamber 836.

More particularly, the locomotion motor 800 preferably includes a pairof cable connection assemblies 943 forming a seal about respective onesof the cables 938 and 940, such that ingress of contaminants into themotor chamber 836 is at least substantially prohibited. The connectionassemblies 943 are preferably identical in constructions, but theprinciples of the present invention apply to dissimilar assemblies or toonly a single assembly.

Preferably, each cable connection assembly includes a cable receiver 944defining a cable opening 946. The cables 938 and 940 extend generallyaxially through the respective receivers 944 and cable openings 946 enroute to the connection interface 942.

Most preferably first side end plate 838 integrally defines the pair ofcable receivers 944. More particularly, the cable receivers 944 areintegrally formed with the end plate body 838 a.

Each cable connection assembly 943 further preferably includes a sleeve948 at least substantially circumscribing the respective one of thecables 938,940 and received in a corresponding one of the cable openings946. The sleeves 948 are preferably overmolded and comprise acompressible, resiliently deformable material such as rubber.

In a preferred embodiment, each cable connection assembly 943 furtherincludes a compressible grommet 952 at least substantiallycircumscribing the corresponding cable 938,940 and being at least inpart received in the corresponding cable opening 964. Each grommet 952at least substantially circumscribes the corresponding sleeve 948.

The grommets 952 preferably comprise a compressible, resilientlydeformable material suitable for sealing purposes. For instance, thegrommets might comprise nitrile or a fluoroelastomer such as Viton®.

Preferably, the compressible material forming the sleeves 948 is lessdeformable (e.g., is a higher durometer material) than that of thegrommets 952.

As best shown in FIGS. 37 and 43, each receiver 944 preferably includesan axially extending sidewall 950 presenting an axially tapered innerface 951. The inner face 951 preferably presents a broader face end 951a and a narrower face end 951 b. The narrower face end 951 b ispreferably oriented toward the motor chamber 836.

Similarly, each grommet 952 is preferably generally axiallyfrustoconical or tapered in form so as to present a broader grommet end952 a and a narrower grommet end 952 b. The narrower grommet end 952 bis preferably oriented toward the motor chamber.

Furthermore, although the grommet 952 is preferably frustoconical,non-conical or non-frustoconical (e.g., cylindrical) grommets may beused without departing from the scope of some aspects of the presentinvention.

In a preferred embodiment, each of the sidewalls 950 of the cablereceivers 944 has a threaded outer face 954 defining a plurality ofexternal threads 954 a. Furthermore, the cable connection assemblies 943each preferably include a respective nut 956 having internal threads957, such that the nut 956 may be threadably secured to thecorresponding cable receiver 944. That is, the internal threads 957 ofeach nut 956 are preferably configured to engage the external threads954 a of the corresponding cable receiver 944.

Each nut 956 preferably at least substantially circumscribes thecorresponding one of the grommets 952, the corresponding one of thesleeves 948, and the corresponding one of the cables 938,940.

As will be described in greater detail below, each grommet 952 ispreferably compressed between the sleeve 948 and the sidewall 950 of thecorresponding cable receiver 944 to tightly secure the correspondingcable 938 or 940 and seal the motor chamber 836 against ingress ofcontaminants through the corresponding cable opening 946.

For instance, securement of the nuts 956 on the receivers 944 preferablyprevents axially outward shifting of the corresponding grommets 952.

Furthermore, progressive threading of a given one of the nuts 956 ontothe corresponding one of the receivers 944 results in progressivecompression of the corresponding grommet 952 (and, secondarily, of thesleeve 948). More particularly, each nut 956 presents a grommet-engagingface 956 a. Each grommet 952 presents a nut-engaging face 952 c. Eachgrommet 952 is configured to shift axially into the corresponding cableopening 946 and furthermore be compressibly deformed upon correspondingaxial shifting of the corresponding nut 956 and engagement of thenut-engaging face 952 c and the grommet-engaging face 956 a.

In a preferred embodiment, a friction-reducing washer 958 is providedbetween each nut 956 and grommet 952 (or, more particularly, betweeneach nut-engaging face 952 c and the corresponding grommet-engaging face956 a) to reduce the friction generated between the nut 956 and thegrommet 952 as torque is applied to the nut 956 (e.g., during threadingor unthreading of the nut 956 onto or off of the corresponding cablereceiver 944). In view of this preferred configuration, it isparticularly noted that engagement of the faces 952 c and 956 a, asdescribed above, is not necessarily direct. That is, such engagement mayoccur through an intermediate structure such as one of the preferredfriction-reducing washers 958.

It is also noted that the previously described coordinating, generallytapered shapes of the inner faces 951 of the receivers 944 and of thegrommets 952 facilitate the above-described shifting and compression,although such effects would be possible without the preferred generallytapered shapes.

In a preferred embodiment, as best shown in FIG. 34, an O-ring 959circumscribes each cable receiver 944 to provide a seal between thefirst side end plate 838 and the corresponding nut 956.

The above-described means of integrally sealing the cables 938 and 940provides several advantages relative to conventional cableinterconnection and sealing means. Among other things, for instance,fewer seals are required, fewer overall components are required, and theaxial envelope needed for the interconnection is reduced. The latter ofthese advantages is particularly beneficial in applications like that ofthe locomotion motor 800, in which axial space is at a premium.

Locomotion Sensor Assembly

In a preferred embodiment and as best shown in FIGS. 35, 36, and 39-41,the locomotion motor 800 includes a locomotion output encoder assembly960. The encoder assembly 960 preferably senses the speed and directionof the output shaft 956 (which in turn can be used, along withinformation from the other locomotion moor, to sense the speed anddirection of the robot 10).

The encoder assembly 960 preferably includes a rotatable encoder hub 962and a sensed element 964 secured to the encoder hub 962 to rotatetherewith.

The encoder assembly 960 further preferably includes a sensor assembly966 that is stationary relative to the encoder hub 962 and the sensedelement 964. The sensor assembly 966 is configured to sense the sensedelement 964 and, in turn, the rotation of the encoder hub 962. Mostpreferably, the sensor assembly 966 comprises a printed circuit boardassembly. The sensor assembly 966 thus preferably includes a printedcircuit board 968 and at least an encoder chip 970 and a connector 972,the latter two of which are mounted on the printed circuit board 968.The sensor assembly 966 also preferably includes a printed circuit boardholder 974.

In a preferred embodiment, the encoder hub 962 is mounted on the outputshaft 956 to rotate therewith. More particularly, the encoder hub 962preferably includes a radially extending base plate 976, a generallycircumferential sidewall 978, and a circumferential center wall 980. Thebase plate 976 preferably presents a wheel-facing side 982 and anaxially opposite gearbox-facing (or housing-facing) side 984. Thecircumferential sidewall 978 preferably extends generally axiallyoutwardly from the wheel-facing side 982. The circumferential centerwall 980 preferably extends axially inwardly from the gearbox-facingside 984 and cooperates with the base plate 973 to define an interiorcontact surface 986 that fixedly engages the output shaft 956.

The dust cover 868, the gearbox case 962, and the gearbox-facing (orhousing-facing) side 984 of the encoder hub 962 preferably cooperativelydefine an encoder chamber 985. The sensed element 964 is preferablymounted to the gearbox-facing (or housing-facing) side 984 so as tocircumscribe the center wall 980, face the gearbox case 862, and bedisposed within the encoder chamber 985.

The sensed element 964 is preferably secured by means of apressure-sensitive adhesive, although other securement means arepermissible.

In a preferred embodiment, the sensed element 964 comprises at least oneof (most preferably both) a position indicator and a directionindicator. For instance, in a preferred embodiment, the sensed element964 comprises a reflective code disc. Most preferably, the reflectivecode disc is a window-type decal including hundreds of lines 988. In apreferred embodiment, for instance, the reflective code disc includesone thousand and twenty-four (1024) lines per revolution.

In a preferred embodiment, as shown in FIG. 35 and others, the outputholder 872 of the gearbox case 862 includes a radially extendingsidewall 990 defining an output shaft opening 992 and presenting anouter side face 994 facing the wheel 16.

The output shaft 956 preferably extends through the output shaft opening992.

The sensor assembly 966 is preferably mounted to the outer side face 994of the output holder 872 so as to be fixed relative to the (rotating)output shaft 956 and disc 964.

More particularly, in a preferred embodiment and as shown in detail inFIG. 39, the printed circuit board 968 and the printed circuit boardholder 974 each include a corresponding pair of fastener-receiving holes996 and 998, respectively, that correspond to a pair of apertures 1000formed through the sidewall 990 of the output holder 872. Fasteners 1002extend though the holes 996 and 998 and apertures 1000 to secure theprinted circuit board holder 974 to the output holder 872.

In a preferred embodiment, the printed circuit board holder 974 includesa radially extending base plate 1004, a pair of axially extending sidetabs 1006, and a wire routing extension 1008 extending axially andradially away from the base plate 1004. The printed circuit board 968 ispreferably secured to the printed circuit board holder 974 via thefasteners 1002 and the side tabs 1006. Alternative holder designs andsecurement means are permissible according to some aspects of thepresent invention, however.

In a preferred embodiment, the sensor assembly 966 is radially shiftableso as to ensure radial alignment between the encoder chip 970 and thesensed element (i.e., the reflective code disc) 964. In a preferredembodiment, for instance, the fastener-receiving holes 996 and 998 areoversized relative to the apertures 1000 (see FIG. 39), enabling therelative position of the printed circuit board holder 974 to be shiftedprior to insertion and/or tightening of the fasteners 1002. Other meansof adjustably positioning the printed circuit board holder arepermissible according to some aspects of the present invention, however.For instance, the fastener-receiving holes could be in the form ofradially extending slots.

The above-described preferred configuration also enables circumferentialadjustability of the sensor assembly 966.

In a preferred embodiment, the printed circuit board 968 includes anFR-4 laminate base with a one (1) oz copper foil. The printed circuitboard 968 is preferably single-sided and semi-circular in shape, with aradial width of about eight-tenths (0.8) inch and a length of about oneand five tenths (1.5) inches. Other configurations and sizes arepermissible according to some aspects of the present invention, however.For instance, the board could use an alternative glass-reinforced epoxylaminate backbone, a different amount of copper, and/or have differentdimensions.

In a preferred embodiment, the wheel 16 is supported on a wheel hub1009. The encoder hub 962 at least substantially circumscribes the wheelhub 1009. Rotation of rotor 810, the output shaft 956, and, in turn, thecorresponding wheel 16, preferably causes corresponding equivalentrotation of the encoder hub 962 and the sensed element 964. Suchrotation is detected by the encoder chip 970 on the printed circuitboard 968.

Although the above-described direct transfer of rotation from the outputshaft 956 to the sensed element 964 is preferred, it is permissibleaccording to some aspects of the present invention for an indirectsystem to be provided. Furthermore, the rotation might be non-equivalent(e.g., proportional), in which case the output would require additionalcalibration.

In a preferred embodiment, the dust cover 868 protects the encoderassembly 960 from ingress of external contaminants (e.g., dirt flung bythe corresponding wheel 16). For instance, as noted previously, the dustcover 868 preferably engages the gearbox case 862 along a dustcover-gearbox case interface 869 b to thereby at least substantiallyprevent contaminants passing across the dust cover-gearbox caseinterface 869 b. More particularly, in a preferred embodiment and asbest shown in FIGS. 33 and 34, the output holder 872 presents a pair ofannular shoulders 1010 and 1012 and a circumferential face 1014extending between and interconnecting the shoulders 1010 and 1012. Thedust cover 868 preferably defines corresponding first and second annularshoulders 1016 and 1018 and a circumferential face 1020 extendingbetween and interconnecting the shoulders 1016 and 1018. The shoulder1010 preferably engages the shoulder 1016, while the circumferentialface 1014 engages the circumferential face 1020.

Thus, the dust cover-gearbox case interface 869 b preferably has agenerally labyrinthine form, including a generally axially extendingfirst section 869 c along the interface between faces 1014,1020 and agenerally radially extending second section 869 d along the interfacebetween shoulders 1010,1016. Thus, the second section 869 d ispreferably oriented generally orthogonally relative to the first section869 c.

In a preferred embodiment, the housing 833 preferably defines a sealface 1022. Most preferably, the dust cover 868 defines the seal face1022. An annular seal 1024 is preferably positioned between the encoderhub 962 and the seal face 1022.

The seal 1024 is preferably configured to statically engage the sealface 1022 of the dust cover 868 along a generally arcuate housing-sealinterface 1026 to thereby at least substantially prevent contaminantspassing across the housing-seal interface 1026. Furthermore, the seal1024 is configured to dynamically engage the sidewall 978 of the encoderhub 962 along a generally arcuate hub-seal interface 1028, to thereby atleast substantially prevent contaminants passing across the hub-sealinterface 1028. The encoder hub 962 thereby preferably both supports thesensed element 964 and forms a dynamic seal.

The seal 1024 preferably comprises a compressible material suitable forsealing purposes (e.g., nitrile or a fluoroelastomer such as Viton®).

Thus, in a preferred embodiment, multiple sealing mechanisms areprovided. For instance, the aforementioned flange 874 and O-ring 884cooperatively seal the shell-dust cover interface 869. The dustcover-gearbox case interface 869 b defines an internal labyrinth betweenthe output holder 872 of the gearbox case 862 and the dust cover 868.The sidewall 978 of the encoder hub 962, the seal face 1022 of the dustcover 868, and the seal 1024 provide direct seals (along thehousing-seal interface 1026 and the hub-seal interface 1028) against theenvironment adjacent the corresponding wheel 16.

The preferred forms of the invention described above are to be used asillustration only and should not be utilized in a limiting sense ininterpreting the scope of the present invention. Obvious modificationsto the exemplary embodiments, as hereinabove set forth, could be readilymade by those skilled in the art without departing from the spirit ofthe present invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and access the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention set forth in thefollowing claims.

What is claimed is:
 1. A gearbox assembly comprising: a housing defininga gear chamber, said housing including housing portions abutting eachother along an interface exposed to the gear chamber; a plurality ofgears received in said gear chamber, with the housing being configuredto contain gear lubricant within the gear chamber; and a seal, said sealpositioned along said interface to restrict leakage of lubricant throughthe interface, said housing defining an overflow chamber adjacent saidinterface, such that said interface and said seal are disposed betweenthe gear chamber and the overflow chamber, said housing portionsincluding an upper housing portion, a lower housing portion, and amiddle housing portion, said housing including a plurality of saidinterfaces, said middle housing portion abutting the upper and lowerhousing portions along respective upper and lower ones of saidinterfaces, said gearbox assembly including a plurality of said seals,each of said seals positioned adjacent a corresponding one of saidinterfaces, an upper one of said seals being disposed above an upperchamber lubricant fill line, a lower one of said seals being disposedabove a lower chamber lubricant fill line.
 2. The gearbox assembly asclaimed in claim 1, at least one of said seals at least substantiallycircumscribing the gear chamber, said overflow chamber being positionedradially outside the at least one seal.
 3. The gearbox assembly asclaimed in claim 2, said overflow chamber extending along only a part ofsaid at least one seal.
 4. The gearbox assembly as claimed in claim 2,said overflow chamber being positioned at least in part below acorresponding one of the interfaces.
 5. The gearbox assembly as claimedin claim 1, said overflow chamber and said lower one of said seals beingpositioned adjacent the lower interface.
 6. The gearbox assembly asclaimed in claim 1, said gearbox chamber including— an upper chamberdefined by the upper and middle housing portions, and a lower chamberdefined by the middle and lower housing portions.
 7. The gearboxassembly as claimed in claim 6, said lower one of said seals at leastsubstantially circumscribing the lower chamber, said overflow chamberbeing positioned radially outside the lower one of said seals.
 8. Thegearbox assembly as claimed in claim 6, said upper chamber and saidlower chamber being at least substantially fluidly sealed relative toeach other.
 9. The gearbox assembly as claimed in claim 6, said overflowchamber being defined at least in part below the lower one of saidinterfaces.
 10. The gearbox assembly as claimed in claim 1, said middlehousing portion comprising a single, integrally formed structure. 11.The gearbox assembly as claimed in claim 1, said middle and lowerhousing portions cooperatively defining the overflow chamber.
 12. Thegearbox assembly as claimed in claim 1, said overflow chamber having agenerally elongated form.
 13. The gearbox assembly as claimed in claim12, said overflow chamber extending generally perimetrically around atleast part of the gear chamber.
 14. The gearbox assembly as claimed inclaim 1, at least one of said seals comprising an O-ring.